Canon EOS 60D, Backgrounds

When taking pictures, we usually pay close attention to our subject. This, of course, is a wise thing to do when using your camera, but it’s also very important (and sometimes even more important) to pay attention to the background or backdrop behind your subject (Figure 8.3). The background can make or break your photograph. You should be careful of anything behind your subjects that could appear to be sticking out of their heads (trees are a common culprit) or of busy backgrounds that could compete with whatever or whoever you are photographing.

This woman was framed in the photo so that no distracting elements were directly behind her head.
FIGURE 8.3 This woman was framed in the photo so that no distracting elements were directly behind her head.

Canon EOS 60D, Depth of Field

Selective focusing with a wide aperture can add a lot of creativity to your images. You are telling the viewer where you want the focus of the image to be, and the meaning and story change depending on what is in focus. Using a telephoto lens can compress your background even more, decreasing the depth of field and making the background or foreground even blurrier. But take into consideration that just because your background or foreground is blurry, it doesn’t mean you can’t show detail in those areas (Figure 8.1).

A wide aperture and a long lens were used in this image to create a blurred background; the man in the background is still fully visible, even though the focus is on the woman.
FIGURE 8.1 A wide aperture and a long lens were used in this image to create a blurred background; the man in the background is still fully visible, even though the focus is on the woman.

If you wanted the entire image to be in focus, you would use a smaller aperture. Images with great depth of field, such as a landscape or an image with a lot of detail, direct the viewer to look at the entire scene (Figure 8.2).

BOKEH

The term “bokeh” (pronounced “boh-keh”) refers to the out-of-focus area in an image, or the aesthetic quality of the blur. Different lenses will result in different qualities of bokeh, and it is usually more visible in images with very shallow depth of field.

In order to capture all the details in this image, I used a small aperture so that the majority of the scene was in focus.
FIGURE 8.2 In order to capture all the details in this image, I used a small aperture so that the majority of the scene was in focus.

Nikon D7000, Sharp Focus: Using a Tripod

There are a couple of reasons tripods are so critical to your landscape work, the first being the time of day that you will be working. As we’ll cover later, the best light for most landscape work happens at sunrise and just before sunset. While this is the best time to shoot, it’s also kind of dark. That means you’ll be working with slow shutter speeds. Slow shutter speeds mean camera shake, unless you take precautions. Camera shake equals bad photos.

The second reason is also related to the amount of light that you’re gathering with your camera. When taking landscape photos, you will usually want to be working with very small apertures, as they give you lots of depth of field. This also means that, once again, you will be working with slower-than-normal shutter speeds.

Slow shutter = camera shake = blurry photos.

If you’re serious about landscape photography, then the one tool that all landscape photographers have to have is a good tripod. We might argue over what camera or what lens, but we all agree a tripod is key to getting a good image (Figure 7.1).

There is a funny story behind this image, but first notice that all of these photographers are using tripods at the Moulton Barn in Wyoming. You will also notice that it was a lowlight situation, taking place as soon as the sun came up.
Figure 7.1 There is a funny story behind this image, but first notice that all of these photographers are using tripods at the Moulton Barn in Wyoming. You will also notice that it was a lowlight situation, taking place as soon as the sun came up.

The story regarding Figure 7.1 is that while I thought I was going to beat everyone to the punch and get this shot at just the right time, apparently they had figured this out well before I did and I hadn’t set my alarm quite early enough. I lost my place to four other photographers who had done a little more research. I learned my lesson and it’s never happened since!

So what should you look for in a tripod? Well, first make sure it is sturdy enough to support your camera and any lens that you might want to use. Most manufacturers will list the weight limits by model. Next, check the height of the tripod. There is nothing worse than having to bend over all day to look through your viewfinder. Think about getting a tripod that uses a quick-release head. This usually employs a plate that screws into the bottom of the camera and then quickly snaps into place on the tripod. This will be especially handy if you are going to move between shooting by hand and using the tripod. Finally, consider the weight of the tripod. If you’re traveling a lot or backpacking, having a heavy tripod is a real burden. Carbon fiber tripods are nice since they are very light and incredibly sturdy, but of course that combination comes at an increased cost.

VR lenses and tripods don’t mix

Turn off the Vibration Reduction feature when using a tripod.
Figure 7.2 Turn off the Vibration Reduction feature when using a tripod.

If you are using Vibration Reduction (VR) lenses on your camera, you need to remember to turn this feature off when you use a tripod. This is because Vibration Reduction can, while trying to minimize camera movement, actually create movement when the camera is already stable. To turn off the VR feature, just slide the VR selector switch on the side of the lens to the Off position (Figure 7.2).

Canon PowerShot G12, Watching Your Videos

There are a couple of different options for you to review your video once you have finished recording. The first is probably the easiest: Press the Playback button to bring up the recorded image on the LCD screen, and then use the Set button to start playing the video. The Left/Right buttons act as the video controller and allow you to rewind and fast-forward as well as stop the video altogether.

If you would like to get a larger look at things, you will need to either watch the video on your TV or move the video files to your computer. To watch on your TV, connect an HDMI cable to the HDMI Out port, or connect the video cable that came with the camera to the A/V Out/Digital port (Figure 11.4).

The video ports on the G12.
Figure 11.4 The video ports on the G12.

Once you’ve connected to your TV, simply use the same camera controls that you used for watching the video on the LCD screen.

If you want to watch or use the videos on your computer, you need to download the images using the Canon software or by using an SD card reader attached to your computer. The video files will have the extension “.mov” at the end of the file name. These files should play on either a Mac or a PC using software that came with your operating system or that can be downloaded for free (Apple’s QuickTime for Mac and Windows is available at www.apple.com/quicktime/download/).

Canon PowerShot G12, Video Shooting Tips

From a technical standpoint, shooting video with the G12 isn’t that much different from capturing stills. The Video mode supports adjustments like white balance settings, the ND (neutral density) filter, and even the Self-Timer feature. Instead, shooting video requires a slightly different mind-set.

Shooting Smooth, not Jerky

My best advice is to take your time and be calm while shooting, as much as possible. If you whip the camera around like a caffeinated toddler, you’ll end up with blurry, nausea-inducing footage. Be deliberate about holding the camera steady and panning slowly and smoothly. Your viewers will thank you.

If possible, set the camera on something when you need to move as you shoot. It’s possible to buy or make rail systems for making smooth dolly moves (a Web search will reveal lots of solutions), but don’t discount anything on wheels you may have at hand (Figure 11.2).

To pan across a scene, I pressed into service one of my daughter’s toy cars.
Figure 11.2 To pan across a scene, I pressed into service one of my daughter’s toy cars.

A Tripod Becomes More Important

In the same spirit as shooting smooth footage, it’s often more important to capture video while the G12 is mounted on a tripod. With video, the motion of the camera is as noticeable as what’s in the frame. A tripod also gives you the opportunity to make sure the camera is level with the horizon. If a tripod isn’t available, I highly recommend bringing up the G12’s Electronic Level on the LCD (press the Display button to view the level, which also makes the grid visible).

Shooting Extra Footage

I’m assuming that you plan to edit your footage later, so here’s another essential tip: Shoot lots of video. Not just of the event happening in front of you, but of what’s going on around it. When my wife and daughter were painting leaves last autumn, I made a point to capture footage of visually appealing things nearby (Figure 11.3). A shot of a lone leaf against the blue sky became a nice place to put a title, for example, and an overhead clip of the leaves and paints provided an establishing shot when segueing between gathering the leaves and painting them. These types of supplemental clips add flavor and texture to your movie.

Shoot plenty of extra video to add visual interest to your movie when editing it.
Figure 11.3 Shoot plenty of extra video to add visual interest to your movie when editing it.

 

Canon PowerShot G12, Locking the Exposure Level

Not everything is automatically locked once you begin recording. The camera tries to dynamically compensate for exposure fluctuations (moving from bright to shaded areas, for example) as you record, which can often be a distraction. Fortunately, you can manually adjust and lock the exposure level before recording. (Changing the setting on the Exposure Compensation dial, however, has no effect.)

Setting the Exposure

Setting the Exposure
Setting the Exposure
  1. With the camera in Movie mode, press the * AE Lock button when the exposure level is to your liking.
  2. With an eye on the exposure shift bar that appears, use the Control dial to adjust the exposure in one-third stop increments.
  3. Press the shutter button to begin recording, or press the * AE Lock button again to disable the lock. Once you do start recording, you can’t adjust the exposure manually.

View Techniques in Action

To see many of the techniques Painting Leaves: http://www.youtube.com/watch?v=sWwCpDLVaEI&hd=1

Canon PowerShot G12, Locking Focus

Normally, the G12 focuses on whatever is in the middle of the screen. You can manually focus the lens before shooting by pressing the MF button and turning the Control dial.

However, once you begin recording, the focus is set: The camera doesn’t adjust the focus if your subject moves toward or away from the camera, which is one of the main drawbacks of shooting video with the G12 versus a dedicated camcorder.

It’s also possible to zoom in (but not out) on your subject while recording, but the zoom is digital, not optical, so the quality won’t be as good. It’s better to frame your subject before you press the shutter button.

Cockroaches (Blattaria)

Cockroaches are among the oldest and most primitive of insects. They evolved about 350 million years ago during the Silurian Period, diverging together with the manrids from an ancestral stock that also gave rise to termites (Boudreaux 1979). Cockroaches are recognized as the order Blattaria. Although the majority of species are feral and not directly associated with people, a few species have evolved in proximity to human habitations, where they have adapted to indoor environments. Their omnivorous feeding behavior, facilitated by their unspecialized chewing mouthparts, has contributed to a close physical relationship between cockroach populations and humans, with resultant chronic exposure of humans to these pests. The presence of some species in the home (e.g., German and brownbanded cockroaches) often is an indicator of poor sanitation or substandard housekeeping.

Although they are primarily nuisance pests, their presence can have important health implications. Cockroaches are generalists that feed on virtually any organic substance grown, manufactured, stored, excreted, or discarded by humans. Consequently, food supplies are at risk of contamination by pathogens associated with cockroaches. Because species that infest structures typically have high reproductive rates, humans commonly are exposed to high levels of potentially allergenic proteins associated with cockroaches, which can lead to significant respiratory ailments. Cockroaches also can serve as intermediate hosts of parasites that debilitate domestic animals.

TAXONOMY

There are about 4000 species of cockroaches worldwide. About 70 species occur in the United States, 24 of which have been introduced from other parts of the world. According to Atldnson et al. (1991), 17 of these species are pests of varying degrees. There are five cockroach families, three of which include most of the pest species: Blattidae, Blattellidae, and Blaberidae. Species in the Cryptocercidae are unusual in that they have gut symbionts similar to those found in termites, and they live in family groups in decaying logs. Members of the Polyphagidae include those dwelling in arid regions, where they are capable of moving rapidly through sand. Species in these two families are rarely pests. The family Blatfidae includes relatively large cockroaches that are the most common peridomestic pests throughout much of the world. Blattellid cockroaches range in length from less than 25 mm (e.g., Supella and Blattella) to 35-40 mm (e.g., Periplaneta and Parcoblatta spp.). Parcoblatta species are feral, occasionally invading homes but seldom reproducing indoors. Blaberid cockroaches range greatly in size and include some of the more unusual species, such as the Cuban cockroach, which is green as an adult, and the Surinam cockroach, which is parthenogenetic in North America. Nearly all of the blaberids that occur in the United States are restricted to subtropical regions and have minor medical or veterinary significance. Taxonomic keys for adults are provided by McKittrick (1964), Cornwell (1968), Roth (1985), and Heifer (1987). A pictorial key for identifying the egg cases of common cockroaches is provided by Scott and Borom (1964).

MORPHOLOGY

Cockroaches have retained their basic ancestral form. The Blattaria are distinguished from other insect orders by morphological characters associated with wing size and venation, biting/chewing mouthparts, and prominent cerci. They differ from other orthopteroid insects by having hind femora which are not enlarged, cerci typically with eight or more segments, a body that is dorsoventrally flattened and generally ovoid, and a head that is largely concealed from above by a relatively large pronotum.

A common indicator of cockroach infestations is their egg cases, or oothecae (singular ootheca), purse-shaped capsules that typically contain 5-40 embryos (Fig. 3.1). Coloration ranges from light brown to chestnut brown, depending on the degree of sclerotization. A keel that runs the anterior length of the ootheca permits transport of water and air to the developing embryos. Each embryo is contained in a separate compartment that may or may not be obvious externally. In some species (e.g., German and brownbanded cockroaches) lateral, anterior-to-posterior indentations denote the individual developing embryos. Others have only weak lateral indentations (e.g., brown and smokybrown cockroaches), and still others have no lateral indentations but differ in their symmetry (e.g., Oriental, American, and Australian cockroaches).

The mouthparts of cockroach nymphs and adults are characterized by strongly toothed mandibles for biting and chewing. Maxillary and labial palps are well developed, with five and three segments, respectively. Antennae are long and whiplike, originate directly below the middle of the compound eyes, and consist of numerous small segments. The arrangement of three ocelli near the

Cockroach oothecae (egg cases). A, Australian cockroach (Periplaneta australasiae); B, Brown cockroach (P. brunnea); C, Smokybrown cockroach (P. fuliginosa); D, Oriental cockroach (Blatta orientalis); E, American cockroach (P. americana); F, Brownbanded cockroach (Supella longipalpa); G, German cockroach (Blattella germanica). (Courtesy of the US Public Health Service)
FIGURE 3.1 Cockroach oothecae (egg cases). A, Australian cockroach (Periplaneta australasiae); B, Brown cockroach (P. brunnea); C, Smokybrown cockroach (P. fuliginosa); D, Oriental cockroach (Blatta orientalis); E, American cockroach (P. americana); F, Brownbanded cockroach (Supella longipalpa); G, German cockroach (Blattella germanica). (Courtesy of the US Public Health Service)

antennal sockets is variable: they are well developed in winged species (macropterous) but rudimentary or lacking in species with reduced wings (brachypter0us) or those lacking wings altogether (apterous).

Adults generally have two pairs of wings that are folded fanwise at rest. The front wings, called tegmina (singular tegmen), are typically hardened and translucent, with well-defined veins. The hind wings are membranous and larger. In some species, such as the wood cockroaches (e.g., Parcoblatta species), females are brachypterous and incapable of flight, whereas males are macropterous. Other species, such as the Florida woods cockroach (Eurycot# floridana), have only vestigial wing buds as adult males and females. In cockroaches, all three pairs of legs are well developed, with large coxae and slender, long segments that aid in the rapid running that is characteristic of these insects. Each femur has two longitudinal keels that typically are armed with spines. The tibiae are often heavily spined and are used for defense against predators. Each tarsus consists of five segments with a pair of claws and may bear a padlike arolium that aids in walking on smooth surfaces. Ventral pads, or pulvilli, are present on tarsomeres 1-4. A pair of caudal cerci have small ventral hairs that are sensitive to vibrations caused by lowfrequency sound and air movement; their stimulation initiates an escape response.

The posterior end of the abdomen of some nymphs and all males bears a pair of styli (singular stylus) between the cerci, arising from the sternum of the ninth abdominal segment. In winged species, the styli may be apparent only when viewed ventrally. The structure of the styli serves to distinguish males from females. Generally the males also can be recognized by their more slender bodies, with laterally tapered and dorsally flattened external genitalia (terminalia). The terminalia of the more robust females are notably broader than in males and bear a conspicuous subgenital plate that is rounded or keel-like when viewed ventrally. Associated with this plate is a relatively large genital chamber (genital pouch) in which the ootheca develops. For a more detailed description of cockroach genitalia, see McI~ttrick (1964) or Cornwell (1968). Nymphal stages are similar in appearance to adults, but they lack wings, have incompletely developed genitalia, and may vary markedly in color from the adult.

LIFE HISTORY

Cockroaches are paurometabolous insects. The immature cockroaches generally are similar in appearance to the adults except for their undeveloped sexual organs and lack of fully developed wings (Fig. 3.2). Reproduction in cockroaches is typically sexual, although parthenogenesis is reported in a few species. Comparative life history data for some of the more common cockroach pests are provided in Table I.

In cockroaches, embryogenesis and oviposition occur in one of three ways. Most species are oviparous, including

Developmental stages of cockroaches, represented by Periplaneta brunnea. Left to right: first, second, third, and fourth nymphal instars; adult female, adult male. (Courtesy of Daniel R. Suiter)
FIGURE 3.2 Developmental stages of cockroaches, represented by Periplaneta brunnea. Left to right: first, second, third, and fourth nymphal instars; adult female, adult male. (Courtesy of Daniel R. Suiter)

all Periplaneta species and the Oriental and brownbanded cockroaches. Eggs of oviparous species are protected inside a thick-walled, impermeable ootheca which is deposited soon after it is formed. Embryonic development occurs external to the female. The German cockroach is oviparous, but the female carries the ootheca protruding from the genital chamber until just hours before hatching occurs. The ootheca is softer than in Periplaneta species, allowing uptake of water and nutrients from the genital pouch. A few cockroaches, such as Blaberus species and the Surinam cockroach, are pseudo-ovoviviparous, in that females produce an ootheca which is extruded, rotated, and then retracted into the genital pouch. The eggs are incubated internally until hatching. The only known pseudo-viviparous species is Diploptera punctata, a pest species in Hawaii; the embryos hatch while still in the genital pouch. Embryogenesis takes 1-8 weeks, depending on the species.

The number of nymphal instars varies from 5 to 13, depending on the species, nutritional sources, and microclimate. Development of pestiferous species through the nymphal stadia requires from 6-7 weeks for German cockroaches to well over a year for Periplaneta species and other larger cockroaches. Typically, the nymphs exhibit strong aggregation tendencies, governed largely by aggregation pheromones. These pheromones act as locomotory inhibitors; when cockroaches perceive the pheromone they become relatively stationary. Studies of various species have shown that development to the adult stage is quicker when nymphs are reared in groups rather

I Life Histories of Selected Common Species of Cockroaches, Showing the High Degree of Variability Within Species Due to Environmental Temperatures and Nutritional Availability

 

than in isolation. However, aggregation does have a biological cost; those reared in groups typically are smaller in size, and cannibalism may occur. Longevity of cockroaches varies from several weeks to over a year.

BEHAVIOR AND ECOLOGY

Mating in cockroaches generally is preceded by courtship behavior facilitated by sex pheromones. In some species a blend of volatile compounds is produced by virgin females to attract and orient males (e.g., Periplaneta species and the brownbanded cockroach). In the German cockroach, the sex pheromone is a blend of nonvolatile and volatile cuticular components that elicits courtship by males following palpation of the female’s integument by the male’s antennae. Once courtship is initiated in the male, he turns away from the female and raises his wings to expose dorsal tergalglands; the female feeds on pheromones from these glands as the male grasps her genitalia with his pair of caudal claspers. Most species copulate in an end-to-end position. During the hour or so that follows, a spermatophore is formed and passed from the male into the genital chamber of the female. Only about 20% of females mate again after the first gonotrophic cycle.

Cockroaches can be categorized ecologically as domestic, peridomestic, or feral. Domestic species live almost exclusively indoors and are largely dependent on humans for resources (food, water, and harborage) for survival. They rarely are able to maintain themselves outdoors. Although this group contains the smallest number of species, it presents the greatest concern to human health. Domestic species include the German and brownbanded cockroaches. Peridomestic species are those which survive in or around human habitation. Although they do not require humans for their survival, they are adept at exploiting the amenities of civilization. This group is represented by American, Australian, brown, and smokybrown cockroaches (all Periplaneta species), the oriental cockroach, and the Florida woods cockroach. Feral species are those in which survival is independent of humans. This group includes more than 95% of all species in the world. Only a few occur indoors as occasional and inadvertent invaders that typically do not survive in a domestic environment. They are of little or no medical importance.

Cockroach behavior and survival are strongly influenced by their need for food, water, and safe harborage from potential predators and detrimental microclimates. They are omnivorous and will consume virtually any organic matter, including fresh and processed foods, stored products, and even book bindings and pastes on stamps and wallpaper when more typical foodstuffs are not available. Cockroaches have the same general problems with water balance as do other terrestrial arthropods. Their relatively small size results in a high surface area to volume ratio and a high risk of losing water through respiration, oral and anal routes, or the cuticle. Temperature, air flow, relative humidity, and availability of liquid water greatly affect water regulation.

As a result of these physiological considerations, physical constraints of the environment usually determine habitat preferences of cockroaches in and around structures. Oriental and American cockroaches, for example, require high moisture and occur in damp terrestrial environments such as septic tanks and municipal sewer systems. Brown, smokybrown, and Florida woods cockroaches occur in a wider range of habitats associated with trees, wood and leaf piles, wall voids, and foundation blocks of buildings. Brownbanded cockroaches are more tolerant of drier conditions and commonly occur in kitchens, pantries, and bedrooms. German cockroaches occupy harborages near food and water. Consequently, they are found primarily in kitchens and pantries, and secondarily in bathrooms, when their populations are high. In mixed populations of German and brownbanded cockroaches, the German cockroach tends to outcompete the brownbanded cockroach within 9 months.

Cockroaches are adept crawlers and are capable of rapid movement even across windows and ceilings. Flight ability varies with species. Some are incapable of flight except for crude, downward gliding used as an escape behavior. Others are weak fliers, occasionally seen flying indoors when disturbed. Still others are relatively strong fliers that are particularly active at sunset, when they may be attracted indoors by lights and brightly lit surfaces. Attraction to light is especially common in the Asian, Surinam, and Cuban cockroaches and in many of the wood cockroaches (Parc0blatta species).

Pestiferous cockroaches that occur indoors are typically nocturnal and tend to avoid lighted areas. This enables them to increase their numbers and become established in structures before human occupants even become aware of their presence.

COMMON COCKROACH SPECIES

The following 11 species of cockroaches are commonly encountered by homeowners in the United States and are the ones most frequently brought to the attention of medical entomologists.

Oriental cockroach (Blatta orientalis)

This peridomestic cockroach (Fig. 3.3) is believed to have originated in northern Africa and from there spread to Europe and western Asia, South America, and North America. It is a relatively lethargic species that prefers cooler temperatures than does the German cockroach and is primarily a concern in temperate regions of the world. Adults are black and 25-33 mm long. Males are winged but do not fly, and females are

Oriental cockroach (Blattella orientalis), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.3 Oriental cockroach (Blattella orientalis), female. (Courtesy of the University of Florida/IFAS)
American cockroach (Periplaneta americana), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.4 American cockroach (Periplaneta americana), female. (Courtesy of the University of Florida/IFAS)

brachypterous. Their tarsi lack aroliar pads, precluding this cockroach from climbing on smooth vertical surfaces. Oothecae are 8-10mm long, each typically containing 16 eggs. Also commonly lmown as waterbug, this species is usually associated with damp or wet conditions, such as those found in decaying wood, heavy ground cover (e.g., ivy) , water meter boxes, and the lower levels of structures. It infests garbage chutes of apartment complexes, sometimes reaching upper floors. Development is slow compared to that of most other species, requiring about a year depending on temperature conditions. Adults may live for many months. Mobility is fairly restricted, malting control easier than for most other species. This species is rarely seen during the daytime.

American cockroach (Periplaneta americana)

The American cockroach (Fig. 3.4) is a large species with adults 34-53 mm in length. It is reddish brown, with substantial variation in light and dark patterns on the pronotum. Adults are winged and capable of flight. Nymphs typically complete development in 13- 14months while undergoing 13molts. Adults live an average of 15 months, but longevity may exceed 2 years. Females drop or glue their oothecae (8 mm long) to substrates within a few hours or days of formation. Each ootheca has 12-16 embryos. A female generally produces 6-14 egg cases during her life (mean of 9).

The American cockroach is perhaps the most cosmopolitan peridomestic pest species. Together with other closely related Periplaneta species, P. americana is believed to have spread from tropical Africa to North America and the Caribbean on ships engaged in slave trading. Today this species infests most of the lower latitudes of both hemispheres and extends significantly into the more temperate regions of the world.

The habitats of this species are quite variable. American cockroaches infest landfills, municipal sewage systems, storm drainage systems, septic tanks, crawl spaces beneath buildings, attics, tree holes, canopies of palm trees, voids in walls, ships, electronic equipment, caves, and mines. Studies conducted in Arizona indicated movement by a number of individuals several hundred meters through sewer systems and into neighboring homes. This species often can be seen at night on roofs and in air stacks or vents of sewage systems, through which they enter homes and commercial buildings. Entrance also is gained to homes through laundry vent pipes and unscreened or unfiltered attic ventilation systems. This cockroach is known to move from crawl spaces of hospitals via pipe chases into operating theaters, patients’ rooms, storage facilities, and food preparation areas. Consequently, the potential of this cockroach for disseminating pathogenic microorganisms can be a significant concern for health care personnel.

Australian cockroach (Periplaneta australasiae)

Adult body coloration is similar to that of the American cockroach, but with paler lateral markings on the upper edges of the tegmina (Fig. 3.5). The pronotum is tinged with similar coloration. Adults are slightly smaller than American cockroaches, measuring 32- 35 mm in length. Females mature in about 1 year and typically live for another 4-6 months. A female can produce 20-30 oothecae during her lifetime; the ootheca is about 11 mm long and contains about 24embryos. Embryonic development requires about 40 days. Nymphs are strikingly mottled, distinguishing them from nymphs of other Periplaneta species.

This peridomestic species requires somewhat warmer temperatures than the American cockroach and does not occur in temperate areas other than in greenhouses and

Australian cockroach (Periplaneta australasiae), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.5 Australian cockroach (Periplaneta australasiae), female. (Courtesy of the University of Florida/IFAS)
Brown cockroach (Periplaneta brunnea), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.6 Brown cockroach (Periplaneta brunnea), female. (Courtesy of the University of Florida/IFAS)

other pseudotropical environs. In the United States, outdoor populations are well established in Florida and along the coastal areas of Louisiana, Mississippi, Alabama, and Georgia. It commonly is found in environments similar to those inhabited by the smokybrown cockroach. In situations where both species occur (e.g., tree holes, attics), the Australian cockroach tends to displace the smokybrown. It can be a serious pest in greenhouses and other tropical environments in more temperate latitudes, where it can cause feeding damage to plants, notably seedlings.

Brown cockroach (Periplaneta brunnea)

The brown cockroach (Fig. 3.6) is smaller than the American cockroach (33-38 mm), and its pronotal markings are more muted. The most apparent diagnostic characteristic for separating these two species is the shape of the last segment of the cercus; in the brown cockroach, the length is about equal to the width, whereas in the American cockroach the length is about 3 times the width. The ootheca of the brown cockroach usually is larger (7-13 vs 8 ram) and contains more embryos (24 vs 16). The brown cockroach affixes its oothecae to substrates using salivary secretions. They give the ootheca a grayish hue not typical of other Periplaneta species that attach their oothecae with salivary secretions. This species is more subtropical than the American cockroach, occurring throughout the southeastern United States, where it infests homes and outbuildings. It is less frequently associated with sewage than is the American cockroach. Because of its similar appearance to the American cockroach, it is often misidentified and may be more widely distributed than is commonly recognized. In Florida, P. brunnea is commonly found in canopies of palm trees and attics. It also readily infests various natural cavities and those in human-associated structures. The oothecae can be useful in differentiating species infesting buildings. Most

Smokybrown cockroach (Periplaneta fuliginosa), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.7 Smokybrown cockroach (Periplaneta fuliginosa), female. (Courtesy of the University of Florida/IFAS)

cockroach oothecae persist in the environment after the nymphs have emerged and provide a history of infestation.

Smokybrown cockroach (Periplanetafuliginosa)

The smokybrown cockroach (Fig. 3.7) has become a major peridomestic pest throughout the southern United States, including southern California, and extends as far north as the Midwestern states. It can be differentiated from the American cockroach by its slightly smaller size (25-33 ram) and uniform dark coloration. Mthough developmental times are quite variable, individuals mature in about 10 months. Adults may live for more than a year. Females produce several oothecae, which are 10-11 mm in length with 20 embryos, at 11-day intervals.

Primary loci for this peridomestic species in the southeastern United States are tree holes, canopies of palm trees, loose mulches such as pine straw or pine bark, and firewood piles. Within structures, P. futiginosa seeks the ecological equivalent of tree holes–areas characterized as dark, warm, protective, and moist, with little air flow and near food resources. These include the soffits (eves) of underventilated attics, behind wall panels, the interstices of block walls, false ceilings, pantries, and storage areas. From these harborages, individuals forage for food and water, generally returning to the same refugia. Mark-release-recapture studies using baited live traps have shown that the median distance traveled between successive recaptures is less than I m but that some adults may forage at distances of more than 30 m.

Florida woods cockroach (Eurycotisfloridana)

This cockroach is restricted to a relatively small area of the United States along the Gulf of Mexico from

Florida woods cockroach (Eurycotisfloridana), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.8 Florida woods cockroach (Eurycotisfloridana), female. (Courtesy of the University of Florida/IFAS)

eastern Louisiana to southeastern Georgia. It is mentioned here only because of its defensive capabilities. It is a large, dark-reddish brown to black cockroach (Fig. 3.8), 30-40 mm long. Although small wing pads are evident, adults are apterous and are relatively slow moving. Oothecae are 13-16 mm long and contain about 22 embryos. E. floridana occurs in firewood piles, mulches, tree holes, attics, wall voids, and outbuildings. Last-instar nymphs and adults, if alarmed, can spray a noxious mix of aliphatic compounds that are both odoriferous and caustic. If this is sprayed into the eyes or onto soft tissues, a temporary burning sensation is experienced. Domestic dogs and cats quicldy learn to avoid this species. Among its common names are the Florida cockroach, the Florida woods roach, the Florida stinkroach, and palmettobug. The last term also is commonly used for other Pcriplaneta species.

Brownbanded cockroach (Supella longipalpa)

Like the German cockroach, this domestic species probably originated in tropical Africa, where it occurs both indoors and outdoors. In North America and Europe it is confined almost exclusively to indoor environments of heated structures. In warm climates, infestations occur particularly in apartments without air conditioning and in business establishments with relatively high ambient temperatures, such as pet stores and animal-care facilities. Adults are similar in size to the those of the German cockroach (13-14.5 mm long) but lack pronotal stripes. Adults have two dark bands of horizontal stripes on the wings (Fig. 3.9), whereas nymphs have two prominent bands running across the mesonotum and first abdominal segment. The brownbanded cockroach derives its name from these bands.

Brownbanded cockroach (Supella longipalpa), female. (Courtesy of the University of Florida/IFAS)
FIGURE 3.9 Brownbanded cockroach (Supella longipalpa), female. (Courtesy of the University of Florida/IFAS)

Populations tend to occur in the nonfood areas of homes, such as bedrooms, living rooms, and closets. Male brownbanded cockroaches occasionally fly and are attracted to lights. Members of this species seek harborage higher within rooms than do German cockroaches. The ootheca is small, only 5 mm long, with an average of 18 embryos and an incubation time of 35-80 days. Females deposit their oothecae by affixing them to furniture, in closets, on or behind picture frames, and in bedding. Transporting S. longipalpa with furniture to new locales is common. Although this species occurs with other cockroaches in homes, the German cockroach often outcompetes it within a few months.

German cockroach (Blattellagermanica)

This cockroach also is known as the steamily in Great Britain. It is believed to have originated in northern or eastern Africa, or Asia, and has spread from there via commerce. The German cockroach is considered to be the most important domestic pest species throughout the developed world. Adults are about 16 mm long, with two dark, longitudinal bands on the pronotum (Fig. 3.10). It requires warm (optimally 30-33°C), moist conditions near adequate food resources. It primarily inhabits kitchens and pantries, with secondary foci in bathrooms, bedrooms, and other living spaces in heavily infested structures. Although this species is nocturnal, like most other cockroaches, some individuals may be seen moving about on walls and in cupboards during the daylight hours where infestations are heavy. Their wing musculature is vestigial, making them unable to fly except for short, gliding, downward movements. B. germanica does not readily move between buildings; however, it does occur in garbage collection containers and outbuildings near heavily infested structures.

German cockroach (Blattella german#a), female. (Courtesy of the University of Florida/IFAS)
HGURE 3.10 German cockroach (Blattella german#a), female. (Courtesy of the University of Florida/IFAS)

The German cockroach has a high reproductive potential. Females produce an ootheca (6-9 ram) containing about 30 embryos within 7-10 days after molting to the adult, or about 2-3 days after mating. The female carries the egg case until a few hours before hatching of the nymphs, preventing access of any oothecal parasitoids or predators. Oothecae are produced at intervals of 20- 25 days, with a female producing 4-8 oothecae during her lifetime. Nymphs complete their development in 7- 12 weeks.

This species is the main cockroach pest in most households and apartment complexes. Control is difficult, in part because of their movement between apartments through plumbing chases in shared or adjacent walls. Researchers studying over 1,000 apartments in Florida concluded that the median number of cockroaches per apartment was >13,000. This high biotic potential makes this species a major nuisance, as well as a pest with implications for human health.

Asian cockroach (Blattella asahinai)

The Asian cockroach is closely related to the German cockroach, from which it is difficult to distinguish morphologically. In fact, Asian and German cockroaches are capable of hybridizing and producing fertile off’- spring, which further complicates their identifications. Techniques have been developed to differentiate these two species and their hybrids based on cuticular hydrocarbons in the waxy layer of the integument.

Despite their morphological similarity, B. asahinai differs from B. germanica in several aspects of its behavior and ecology. It is both a feral and a peridomestic species. Nymphs of the Asian cockroach commonly occur, sometimes in large numbers, in leaf litter and in areas of rich ground cover or well-maintained lawns. Unlike the German cockroach, the adults fly readily and are most active beginning at sunset, when they fly to light-colored walls or brightly lit areas. This behavior can make invasion a nightly occurrence in homes near heavily infested areas. Flight does not occur when temperatures at sunset are below 21°C.

Like those of the German cockroach, Asian cockroach females carry their oothecae until shortly before they are ready to hatch. The ootheca is similar in size and contains the same number of embryos as does that of the German cockroach (38-44). Nymphs are smaller than their B. germanica counterparts and are somewhat paler in appearance. Development from egg to adult requires about 65 days, with females producing up to six oothecae during their life span. Adults also are slightly smaller than those of B. germanica (average of 13 vs 16mm).

The Asian cockroach was first described in 1981 from specimens collected in sugar-cane fields on the Japanese island of Okinawa. When it was first discovered in the United States in 1986, the Asian cockroach was found only locally in three counties in Florida, from Tampa to Lakeland; populations already had become established, with densities as high as 250,000 per hectare. By 1993, this species had spread to at least 30 Florida counties and had infested citrus groves throughout the central part of the state. It feeds on succulent early growth of citrus nursery stock, tassels of sweet corn, strawberries, cabbage, tomatoes, and other agricultural products, although there has been no evidence of significant economic damage.

Infestations of apartments by B. asahinai have become common in central Florida. This cockroach also has become an increasing problem in warehouses, department stores, hotels, fast-food establishments, automobile dealerships, and other businesses with hours of operation that extend beyond dusk.

Surinam cockroach (Pycnoscelus surinamensis)

This species is believed to have originated in the Indo- Malayan region. It commonly occurs in the southeastern United States from North Carolina to Texas. The adults are fairly stout, 18-25 mm in length, with shiny brown wings and a black body (Fig. 3.11). Nymphs characteristically have shiny black anterior abdominal segments, whereas the posterior segments are dull black and roughened. In North America this species is unusual in that it is parthenogenetic, producing only female offspring; elsewhere both males and females are found. The ootheca is 12-15 mm long, is poorly sclerotized, and contains about 26 embryos. Oothecae are retained inside the genital chamber, from which the nymphs emerge in about 35 days. Females produce an average of three oothecae and live about 10 months in the laboratory. This cockroach commonly burrows into compost piles and the thatch of lawns. Transfer

Surinam cockroach (Pycnoscelussurinamensis). (Courtesy of the University of Florida/IFAS)
FIGURE 3.11 Surinam cockroach (Pycnoscelussurinamensis). (Courtesy of the University of Florida/IFAS)

of fresh mulch into the home for potting plants can result in household infestations. Adult females fly and are attracted to light. They are most likely to be noticed by homeowners at night when they fly into brightly lit television screens. This species commonly is transported in commercial mulch to more temperate areas of the United States, where it has been known to infest greenhouses, indoor plantings in shopping malls, and ZOOS.

Cuban cockroach (Panchlora nivea)

This medium-sized cockroach (22-24 mm in length) is unusual in that the adults are pale green. The nymphs are dark brown and are found in leaf litter and decaying wood piles. Adults are strong fliers and are attracted to lights. Panchlora nivea is believed to be native to the Caribbean basin, Mexico, Central America, and northern South America. In the United States it occurs commonly in Florida and coastal Louisiana and Texas. This cockroach often is seen in the evening, resting on windows and glass patio doors, apparently drawn to the brightness of indoor lighting.

PUBLIC HEALTH IMPORTANCE

Cockroaches infesting human dwellings and workplaces represent a more intimate and chronic association than do most other pests of medical/veterinary importance. High populations of any cockroach species may adversely affect human health in several ways. These include contamination of food with their excrement, dissemination of pathogens, induced allergies, psychological stress, and bites. Mthough documentation of bites is limited, there are reports of cockroaches feeding on fingernails, eyelashes, skin calluses of hands and feet, and food residues about the faces of sleeping humans, causing blisters and small wounds (Roth and Willis 1957, 1960). There are other accounts of bites around the mouths of infants in heavily infested homes and even in hospitals. American and Australian cockroaches are the most often implicated species. Bites by the Oriental cockroach have resulted in inflammation of the skin, degeneration of epithelial cells, and subsequent necrosis of the involved tissues.

While many individuals develop a tolerance for cockroach infestations, others may experience psychological stress. The level of stress tends to be proportional to the size of the cockroaches and the magnitude of the infestation. An aversion to cockroaches may be so strong that some people become irrational in their behavior, imagining a severe infestation even when there is none. This illusion of abundant cockroaches has caused some families to move out of their homes. High cockroach populations also produce a characteristic odor that can be unpleasant or even nauseating to some people. Foodstuffs may become contaminated with the excrement of cockroaches, which, on subsequent ingestion, may cause vomiting and diarrhea.

The presence of cockroaches in homes does not necessarily imply poor housekeeping. Peridomestic species such as the American and the Oriental cockroach commonly infest municipal sewage systems or septic tanks and may move into homes through sewage lines. Any of the Periplaneta species may develop high outdoor populations, inducing individuals to seek less crowded environments. At such times, they often enter homes through attic vents, breaches in construction joints, or through crawl spaces. This tends to occur in early fall. While they are active at night the smokybrown cockroach, Asian cockroach, and feral wood roaches (Parcoblatta species) often find their way into even the best-kept homes. Adults frequently alight on doors illuminated by entrance lights, or on window screens of lighted rooms. Entrance is gained once the door is opened or by squeezing past window-screen frames.

Poor housekeeping and unsanitary conditions contribute significantly to cockroach infestations. The German cockroach and, to a lesser degree, the brownbanded cockroach are the principal bane of apartment dwellers. Their survival is enhanced by crowded living quarters, associated clutter, and the accumulated organic debris associated with food preparation. Construction practices used to build apartment complexes (e.g., common wiring ducts, sewage lines, and refuse areas) can contribute to the spread of cockroaches in multiunit dwellings.

Bacteria adhering to tarsus of German cockroach (Blattellagermanica). (From Gazivoda and Fish 1985)
FIGURE 3.12 Bacteria adhering to tarsus of German cockroach (Blattellagermanica). (From Gazivoda and Fish 1985)

PATHOGENIC AGENTS

The significance of cockroaches in public health remains controversial despite the logical assumption that they play a role in transmitting pathogenic agents. Given that cockroaches are so closely associated with humans and poor sanitation, the potential for acquiring and mechanically transmitting disease agents is very real. They are capable of transmitting microorganisms (Fig. 3.12) and other disease agents indirectly by contaminating foods or food preparation surfaces.

Table II lists pathogenic organisms that have been isolated from cockroaches in domestic or peridomestic environments. At least 32 species of bacteria in 16 genera are represented. These include such pathogens as Bacillus subtilis, a causative agent of conjunctivitis; Escherichia coli and 9 strains of Salmonella, causative agents of diarrhea, gastroenteritis, and food poisoning; Salmonella typhi, the causative agent of typhoid; and 4 Proteus species, which commonly infect wounds. These isolations primarily have involved American, German, and Oriental cockroaches. Cockroaches also have been found harboring the eggs of 7 helminth species, at least 17 fungal species, 3 protozoan species, and 2 strains ofpoliomyelitic virus (Brenner et al,. 1987; Koehler et al., 1990, Brenner 1995). Researchers in Costa Rica have shown that Australian, American, and Madeira cockroaches become infected with the protozoan Toxoplasmagondii after eating feces of infected cats. This suggests the possibility of cockroach involvement in the maintenance and dissemination of this parasite, which causes toxoplasmosis in humans, cats, and other animals.

Mthough many pathogens have been recovered from natural populations of cockroaches, this does not necessarily mean that cockroaches serve as their vectors. Isolation of pathogens from cockroaches simply may be

Bacteria Pathogenic to Humans That Have Been Isolated from Field-Collected Cockroaches

indicative of the natural microbial fauna and flora in our domestic environment. Under certain circumstances, however, cockroaches have the potential for serving as secondary vectors of agents that normally are transmitted by other means. Anecdotal accounts associating diseases in humans with the occurrence of cockroaches and microbes lend some credence to the hypothesis that these pests can serve as vectors. Burgess (1982) reported the isolation from German cockroaches of a serotype of S. dysenteriae that was responsible for an outbreak of dysentery in Northern Ireland. Mackerras and Mackerras (1948) isolated S. bovis-morbificans and S. typhimurium from cockroaches captured in a hospital ward where gastroenteritis, attributed to the former organism, was common. In subsequent experimental studies, Salmonella organisms remained viable in the feces of cockroaches for as long as 40 days postinfection (Mackerras and Mackerras 1949). Some of the most compelling circumstantial evidence suggesting that cockroaches may be vectors was noted in a correlation between cases of infectious hepatitis and cockroach control at a housing project during 1956- 1962 in southern California (Tarshis 1962). The study area involved more than 580 apartments and 2800 persons; 95% of the apartments had German cockroaches and a lesser infestation of brownbanded and Oriental cockroaches. After pest control measures were initiated, the incidence of endemic infectious hepatitis decreased for i year. When treatments were discontinued during the following year because the insecticide was offensive to apartment dwellers, the cockroach population increased, accompanied by a corresponding increase in the incidence of hepatitis. Effective control measures were applied for the following 2 years, and cockroach populations and cases of infectious hepatitis dropped dramatically while hepatitis rates remained high in nearby housing projects where no pest control measures were conducted.

INTERMEDIATE HOSTS

Cockroaches can serve as intermediate hosts for animal parasites (Table III). Roth and Willis (1960) published an extensive list of biotic associations between cockroaches and parasitic organisms that potentially infest humans. The eggs of seven species of helminths have been found naturally associated with cockroaches. These include hookworms (Ancylostoma duodenale and Necator americanus), giant human roundworm (Ascaris lumbricoides), other Ascaris species, pinworm (Enterobius vermicularis), tapeworms ( Hymenolepis species), and the whipworm Trichuris trichuria. Development of these helminths in cockroaches has not been observed. These relationships probably represent incidental associations with the omnivorous feeding behavior of cockroaches.

However, cockroaches may serve as potential reservoirs and possible vectors through mechanical transfer in areas where a high incidence of these pathogens in humans is accompanied by substantial cockroach infestations. Human infestations by spirurid nematodes associated with cockroaches are known only for the cattle gullet worm (Gongylonema pulchrum) in the United States, Europe, Asia, and Africa and for the stomach worm Abbreviata caucasia in Africa, Israel, Colombia, and Chile. Human cases involving these parasites are rare and cause no pathology.

COCKROACH ALLERGIES

It is only in recent years that the importance of cockroach allergies has been recognized. Allergic reactions result after initial sensitization to antigens following inhalation, ingestion, dermal abrasion, or injection. Allergens produced by cockroaches are rapidly being recognized as one of the more significant indoor allergens of modernized societies. Among asthmatics, about half are allergic to cockroaches. This rate is exceeded only by allergies to house-dust mites. Sensitivity to cockroaches also affects about 10% of nonallergic individuals, suggesting a subclinical level of allergy.

Symptoms exhibited by persons allergic to cockroaches are similar to those described by Wirtz (1980), who reported on occupational allergies in entomologists. They include sneezing and a runny nose, skin reactions, and eye irritation in about two-thirds of the cases. In the more severe cases, individuals may experience difficulty breathing or, even more alarming, anaphylactic shock following exposure to cockroaches. Such allergic reactions can be life-threatening (Brenner et al., 1991).

In recent years, research has focused on determining the specific components of cockroaches that cause allergy. Laboratory technicians exhibit strong allergies to cast skins and excrement of German cockroaches, whereas most patients seen at allergy clinics react primarily to cast skins and whole-body extracts of German cockroaches. Once an individual has become hypersensitized, he or she may experience severe respiratory distress simply by entering a room where cockroaches are held.

Several proteins that can cause human allergies have been identified in the German cockroach. Different exposure histories are likely to result in allergies to different proteins. Cast sldns, excrement, and partially consumed food of cockroaches, in addition to living cockroaches, all produce allergenic proteins. Some are extremely persistent and can survive boiling water, ultraviolet light, and harsh pH changes, remaining allergenically potent for decades. Traditionally, whole-body extracts have been used to screen for allergens in sldn tests and in bronchial challenges for diagnosing cockroach allergies

Cockroaches as Intermediate Hosts of Parasites of Veterinary Importance

(Fig. 3.13). However, use of more specific antigens that become aerosolized in cockroach-infested homes may be more appropriate, as this is likely to be the sensitizing material. Studies with laboratory colonies have shown that a population of several thousand German cockroaches produced several micrograms of aerosolized proteins in 48 hr. Consequently, the presence of cockroaches may have profound respiratory implications for asthmatic occupants of infested structures. For a general discussion on aerosolized arthropod allergens, see Solomon and Mathews (1988).

Development of an allergy to one insect species can result in broad cross-reactivity to other arthropods, including shrimp, lobster, crab and crawfish, sowbugs (isopods), and house-dust mites. Chronic indoor exposure to cockroach allergens, therefore, may have significant and widespread effects on human health.

VETERIN/ dkY IMPORTANCE

Cockroaches serve as intermediate hosts for a number of parasitic worms of animals (Table III). Most of these relationships are of no economic importance. The majority of the parasites are nematodes in the order Spirurida, all members of which use arthropods as intermediate hosts. Species infesting dogs and cats, among other hosts, attach to the mucosa of the gastrointestinal tract, where erosion of tissue may occur at the points of attachment.

Apparatus for conducting allergen tests using cockroaches. (Courtesy of R. J. Brenner, USDA/ARS)
FIGURE 3.13 Apparatus for conducting allergen tests using cockroaches. (Courtesy of R. J. Brenner, USDA/ARS)

Although serious damage seldom occurs, anemia and slow growth may result. Several cockroach-associated nematodes occur in Europe and North America. The esophageal worms Physaloptera rara and P. praeputialis are the most widespread species in the United States. They develop in the German cockroach, field crickets, and several species of beetles.

Poultry also are parasitized by nematodes which undergo development in cockroaches. The Surinam cockroach is the intermediate host for the poultry eye worms Oxyspirura mansoni and O. parvorum. Both occur in many parts of the world. In the United States, their distribution is limited to Florida and Louisiana. The German cockroach has been incriminated as the intermediate host for chicken and turkey parasites, including the stomach worms Tetrameres americana, T. fissispina, and Cyrnea colini; C. colini also develops in the American cockroach. C. colini apparently causes no significant damage to poultry, but Oxyspirura species can cause pathology ranging from mild conjunctivitis to severe ophthalmia with seriously impaired vision. T. fissispina can cause severe damage to the proventriculus of infested birds.

Several nematode parasites of rats and cattle utilize cockroaches as intermediate hosts (Table III). These include G. neoplasticum and Mastophorus muris in rodents. Both genera occur widely in the United States, where they cause no known pathological problems. The gullet worm of cattle, G. pulchrum, has been shown experimentally to undergo development in the German cockroach, although the usual arthropod hosts are coprophagous beetles.

Exotic zoo animals also can become infested with parasitic nematodes for which cockroaches serve as possible intermediate hosts. Protospirura bonnei and P. muricola, for example, have been found in cockroaches collected in cages of monkeys. In a case of “wasting disease” in a colony of common marmosets, more than 50% of German and brownbanded cockroaches captured in the animal room in which they were housed contained the coiled larvae of Trichospirura leptostoma in muscle cells (Beglinger et al., 1988).

Acanthocephalans (thorny-headed worms) commonly infest primates in zoos and research facilities. Prosthenorchis elegans and P. spirula occur naturally in South and Central America. Their natural intermediate hosts are unknown. In captivity, primates become infected after eating any of several cockroach species in which the intermediate stages of the parasite have completed development. Heavily infested primates frequently die within a few days. The proboscis of acanthocephalan adults commonly penetrates the intestines of the primate host, causing secondary infections, perforation of the gut wall, and peritonitis.

One pentastomid (tongue worm), Raillietiella hemidactyli, develops in cockroaches and reptilian hosts. In Singapore, infested geckos are a common occurrence in houses where heavy infestations of R. hemidactyli larvae have been found in American cockroaches. Remnants of cockroaches are found commonly in the guts of these lizards.

For additional information on the veterinary importance of cockroaches, see Chitwood and Chitwood (1950), Roth and Willis (1957), Levine (1968), and Noble and Noble (1976).

PREVENTION AND CONTROL

Traditionally, cockroaches have been controlled using a variety of toxic chemicals applied as residual pesticides to harborage sites or areas frequented by foraging individuals (see Ebling, 1975 and Rust et. al., 1995). Most materials are neurotoxins that disrupt the nervous system, causing locomotory and respiratory failure. These include organophosphates, carbamates, botanicals such as pyrethrins, and pyrethroids. Formulations include wettable powders, emulsifiable concentrates, crack-andcrevice aerosols, dusts, and baits. Several other materials with different modes of action also are currently in use. When ingested, boric acid (delivered as a fine powder or a dilute solution) damages the gut epithelium of cockroaches and kills them by interfering with nutrient absorption. Inorganic silica dust is absorptive, reducing cuticular lipids and causing desiccation. Active ingredients with other modes of action, such as hydramethylnon and sulfluramid, are metabolic inhibitors which disrupt the conversion of food to energy.

The use of baits containing many of the active ingredients mentioned above have been used extensively to control cockroaches. These baits are used indoors in the form of child-resistant bait stations to reduce human exposure. Other bait formulations of gels or pastes are used in crackand- crevice treatments, making them inaccessible to children and pets. Scatter baits are commonly used outdoors to treat mulches and other landscaping materials that harbor cockroaches.

Insect growth regulators (IGRs) can be used to prevent cockroaches from reaching maturity. Two commonly used IGRs are juvenile hormone analogs and chitin synthesis inhibitors. Juvenile hormone analogs regulate morphological maturation and reproductive processes. They are highly specific to arthropods, have very low mammalian toxicity, and are effective at exceptionally low rates of application. Such compounds include hydroprene and fenoxycarb. Chitin synthesis inhibitors prevent normal formation of chitin during molting. These compounds cause many of the affected nymphs to die during the molting process. Males that survive to the adult stage often have reduced life expectancies, whereas females tend to abort their oothecae.

Integrated pest management, which incorporates various control techniques, has contributed significantly to successful control of cockroaches. This approach uses nontoxic agents, such as sticky traps, vacuum devices, diatomaceous earth, or silica-gel repellents and desiccants, and manipulation of harborage sites to reduce or prevent infestations. Desiccants and dusts should be used only in geographic areas or situations with relatively low humidity; high humidity causes these materials to clump and lose their effectiveness. Building designs and construction techniques can significantly influence cockroach survival. By manipulating microclimates in discrete areas of structures frequented by cockroaches, homes and other buildings can be rendered less hospitable to pest species while at the same time greatly reducing aerosolized allergens. Nontoxic repellents can be used to deny access of cockroaches to specific areas.

Biological control of cockroaches has drawn increased attention in recent years. Among the natural agents that have been investigated are parasitic wasps, nematodes, and sporulating fungi. Females of the eulophid wasp Aprostocetus hagenowii and the evaniid wasp Comperia merceti deposit their eggs in the oothecae of certain peridomestic cockroaches. Major shortcomings in utilizing these wasps are difficulties involved in their mass production and the fact that they do not completely eliminate cockroach infestations. However, A. hagenowii has been shown to reduce populations of the peridomestic Periplaneta species following inundative or augmentative releases of this wasp. C. merceti parasitizes oothecae of the brownbanded cockroach and is the only known parasitoid of a domestic species. The use of parasitic nematodes (e.g., Steinernema carpocapsae) and several fungal pathogens that have been isolated from cockroaches has not yet proved to be effective as a practical management tool. Another drawback to their use is the allergenic nature of several components of nematodes and many sporulating fungi that can become airborne and, upon inhalation, cause asthmatic responses in humans.

Models have been developed for predicting population foci of peridomestic cockroaches based on physical characteristics of residential properties (Smith et al., 1995). However, the use of such models is limited by the scope of the data base used in its development and the complexity of the model itself. The use of traps to detect foci of cockroaches and the analysis of trap counts to determine cockroach abundance and distributional patterns can be helpful in assessing the extent of infestations and monitoring the effectiveness of control programs (Brenner and Pierce 1991).

Canon PowerShot G12, Shooting Video

To get started, turn the Mode dial to the Movie shooting position. Much like shooting still photos in Auto mode, the camera attempts to make adjustments automatically before starting to record video. Some aspects, such as manual focus, Macro mode, and to a limited extent, exposure, can be adjusted before you start recording. Just don’t expect to wield the same degree of control over video that you enjoy over still photos.

Capturing Video

The G12 takes a no-frills approach when actually recording video.
Figure 11.1 The G12 takes a no-frills approach when actually recording video.
  1. To focus on something, position it in the middle of the frame and press the shutter button halfway
  2. Once your subject is in focus, fully press the shutter button to begin recording. A red  Rec indicator appears to let you know you’re recording live, along with a count of the time elapsed (Figure 11.1).
  3. To stop the video recording, press the shutter button a second time.

The default shooting mode is Standard; you can also choose Miniature Effect (which not only blurs the edges of the frame, but also speeds up playback), Color Accent, or Color Swap mode by turning the Control dial. I prefer to keep the original video and make any color changes later in computer software such as iMovie (Mac) or Windows Movie Maker (Windows).

Video quality

Here’s some easy advice: Leave the video quality set to the default 1280 x 720. That HD resolution is also known as 720p, and is a major improvement over previous G-series PowerShot cameras. It also records at 24 frames per second (fps), the same projection rate as movies in theaters.

The camera is also capable of shooting video with the dimensions of 640 x 480 or 320 x 240; both sizes record at 30 fps (in NTSC format, used in the Americas and many Asian countries) or 25 fps (in PAL format, used mostly in Europe). However, I can think of only two reasons to do that: If a standard-definition TV is the only device on which you’ll view the footage, or if you want to double the amount of video you can save to the memory card. Cards are getting cheaper every month, so I prefer to buy a new higher-capacity card than give up that much resolution. If you want to see the difference between the two, follow these steps to change the quality.

Setting the Movie Quality

  1. Turn the Mode dial to the Movie shooting position if it’s not already set.
  2. Press the Function/Set button to bring up the shooting options.
  3. Press the Up or Down button to highlight the video quality setting at the bottom of the column.
  4. Use the Control dial to select the desired movie resolution (1280, 640, or 320) and press the Set button again to return to Movie mode.

Memory Cards for Shooting Video

For the best performance when capturing video, buy SDHC cards that are rated Class 4 or higher. They can transfer data faster and come in larger capacities (which is good for shooting stills, too). According to Canon, a 4 GB card will hold approximately 25 minutes of HD video, whereas a 16 GB card will hold about 1 hour 43 minutes’ worth. The 4 GB capacity is important to remember, because the G12 will stop recording automatically once the clip nears that limit; you’d need to start recording a new clip to continue.

Audio

Audio
Audio

The audio captured while shooting video is recorded in stereo using two microphones to the right and left of the hot shoe. And that’s about it. There’s no option to connect an external, directional microphone to the G12 to record better-quality sound. As a result, expect to hear more of what’s closest to the camera (you, and the camera’s controls) instead of the action happening in front of the lens.

The G12 does offer one audio-specific setting: Wind Filter. When it’s enabled, the camera dampens background noise. Press the Menu button and enable or disable the option in the Shooting menu.

Canon PowerShot G12, The My Menu Setting

There are a lot of items in the menu that you can change, but some are used and changed more frequently than others. The My Menu function allows you to place five of your most used menu items in one place so that you can quickly get to them, make your changes, and get on with shooting.

Customizing the My Menu setting

the My Menu setting
the My Menu setting
  1. Press the Menu button and select the tab with the star using the Right or Left button.
  2. Select My Menu settings and press the Function/Set button.
  3. With the Select items option highlighted, press Function/Set (A).
  4. Scroll through the available menu items, and when you highlight one that you want to add, press the Function/Set button (B). A checkmark appears next to the item. (Press the Function/Set button again to remove an item from the list.)
  5. Continue adding the items that you want in the list until you have selected your favorites (up to five of them).
  6. Press the Menu button to return to the previous screen.
  7. You can sort your menu items as you see fit by selecting the Sort menu item and pressing Function/Set. Highlight a command, press Function/Set, and then use the Up and Down buttons to reposition it in the list.
  8. To view your menu by default when you press the Menu button, choose the Set default view item and change its setting to Yes.