Cockroaches - Biology, Identification and Control
John Smith of the Virginia colonies first recorded the name cockroach in the English language in 1624. Apparently he had heard his Spanish companions call such insects “cucaracha.” When one crawled into his food and fouled it with its dung, he called it a “Cacarootch.” By the mid-eighteenth century this name had been changed to cock-roche and later changed to cock roach by Darwin in his famous work, Origin of the Species.
Worldwide there are currently over 3,500 identified species of cockroaches. Most experts feel there are approximately another 3,000 or so species yet to be discovered. Most roaches are tropical in distribution, occupying a variety of habitats in rainforests and similar situations. A total of 69 species occur in the US most of which (approximately two-thirds) have been introduced from other areas. The states totally lacking in native roaches include Idaho, Montana and Wyoming, while Florida has the largest number of native species at 27. Of course, all this adds up to the fact that roaches do best in warm, humid areas with an abundance of food and natural diversity.
Structure and Anatomy leading to Success
Cockroaches are one of the most successful insect groups, with fossil records dating back at about 280 million years. This fact can be attributed to a collection of factors. A major part of this success is due to the external and internal composition of their bodies, a number of which are discussed below.
As with all insects, roaches have a hardened exoskeleton that serves many functions, including protection from water loss and physical injury and internally for muscle attachment, which results in tremendous leverage and strength. Relative to humans, roaches possess great strength and are capable of moving objects up to 20 times their own weight (roaches have more individual muscles than humans-about 900 as opposed to 600). The exoskeleton is made up of several layers, including the outer layer (epicuticle), which is composed of waxes and oils that function to prevent water loss. Because most insects (including roaches) are small, they have relatively little area to store water internally and a relatively large area from which water can evaporate.
As with all insects roaches must periodically molt or shed their nonflexible hardened exoskeleton in order to grow. Growth is accomplished in the immature or nymphal stages. Once a roach reaches the adult stage, molting and growth no longer occur. The primary function of the adult is to mate and reproduce. Beneath the outer waxy layer of the exoskeleton is the exocuticle. This is where the processes of sclerotization and tanning occur. Sclerotization is a hardening-off process where proteins link up. Tanning is the formation of pigments. Immediately prior to molting new layers (epicuticle and endocuticle) are formed beneath the old exoskeleton. When a cockroach gets ready to molt it swallows air, causing an internal pressure which breaks away the old exoskeleton allowing it crawls out (Figure 1). Once out of the old shell a newly molted roach appears as an albino because tanning has not occurred in the exocuticle. Prior to hardening-off, the newly molted roach will again swallow air and stretch the new exoskeleton to a larger size, thus giving it room to grow.
Figure 1. A newly molted cockroach (right) and the old (empty) exoskeleton (left) from which it has emerged. At this point the newly molted roach will swallow air and stretch the new (still soft) exoskeleton to a larger size-thus giving it room to grow.
The head of a cockroach is provided with a variety of sensory organs (Figure 2). The antennae are without a doubt the most important of these structures, serving an array of functions, including the sense of smell, touch, taste and temperature and humidity detection. Compared to humans these functions are vastly more important than the sense of sight. In insects such as roaches, the sense of sight is relatively unimportant. Roaches find their food, water and mates by the sense of smell and taste. Humidity and temperature detection is essential for survival. Roaches are cold blooded (as are all insects) and tend to take on the temperature of their surrounding environment. Seeking a warm environment is essential for mating, feeding and all other physiological activities. If the environment becomes too cold or even cool, their activity tends to cease or slow down to the point of inactivity. Because cockroaches and other insects live in a microclimate (as opposed to the macroclimate we live in), they can readily seek out small warm areas in their environment (e.g. next to electric motors, computers, hot water heaters, radios, TVs).
Also, one of the major problems generally faced by insects is the loss of water from their bodies (dehydration). As previously stated, they are so small they have a relative small area to store water in proportion to the total surface of their body. Of course one of the several ways they fight this battle is to seek out a humid environment to reduce water loss.
There are two types of eyes, namely the compound eyes and simple eyes, or ocelli. Simple eyes do not form images, but serve to detect different intensities of dark and light. The compound eyes are quite large and wrap around the head, allowing roaches at any one time to see in any direction.
Figure 2. Cockroach head--note elongated antennae, white ocelli (inside base of antennae and below top of black compound eyes) and 2 set of palps (elbowed structures on left picture).
Roaches have chewing type mouthparts, including well-developed, sharp-toothed, thick mandibles, which allow them to consume a great variety in food. Behind the mandibles is a pair of arm-like maxillae (mouthparts). These structures serve to manipulate the food and push it into position between the mandibles. In addition these structures possess palp-like structures (maxillary palps) that serve to taste the food. The ends of the maxillae are more or less notched and used to clean the antennae. Anyone who has observed a roach will readily recognize that they are constantly cleaning their antennae (Figure 3).
My wife and I recently witnessed a cockroach’s ability to find and consume food. We sat down to dinner at a well-known restaurant. Right next to our table was a fairly large painting. We decided to have a glass of wine before dinner. Within minutes of arrival of the wine, a German cockroach appeared from beneath the painting and walked out to the middle of our table. Of course, our reaction was not that of normal human beings and we decided to give it some wine. I placed a small drop of wine several inches from the roach which immediately recognized the presence of food through its antennae (smell). It walked over to the drop and tasted it with its maxillary palps. The roach proceeded to suck up the entire drop (which wasn’t much smaller than the roach). It then crawled back to the picture and disappeared. Much to our surprise, within a few minutes the roach reappeared and came back on the table. Of course I gave it another drop and it repeated the entire process of smelling, tasting and consuming the drop. Once finished this time it cleaned its antennae (as shown below) and returned to the picture. A few minutes later the roach dropped from the picture and began to spin on its back. Inebriated? I would think so.
Figure 4. An Oriental cockroach cleaning its antennae.
Flight in most species of roaches is limited or nonexistent. The first pair of wings (tegmina) is typically leathery, typically cover the thorax and abdomen and serve to protect the more delicate second pair of these otherwise relatively vulnerable areas.
The roach leg is elongated, sleek in build and well suited for running. Cockroaches are our fastest running insects, capable of covering several feet in a few seconds. The American cockroach has been clocked at 59 inches per second, which equates to 3.4 miles an hour. This may not seem excessive until their relative speed is considered. This equates to 50 body lengths per second and is about 3 times the speed on a cheetah (fastest land mammal) that can cover 18 body lengths per second at full speed.
The subgenual organs are located at joints on the legs and serve to detect the slightest sound, even the footfalls of other roaches. The tip of each leg is suited with a pair of hook-like structures (tarsal claws) and sticky pads, both of which allow these creatures to claw up (and even upside down) on most surfaces.
A pair of anal cerci (Figure 4) is located on the tip of the abdomen. These peg-like structures serve to detect vibrations. A roach may place them on the ground or hold them in the air and readily detect approaching danger.
Figure 4. Cockroach illustrating anal cerci (lance shaped structures on tip of abdomen).
One of the more important internal organs attributing to cockroach success is the nervous system. A roach is truly a beast with two brains. It has a large paired nerve ganglion in the head and a single ganglion nears the posterior or rear end. These are connected by giant fibers, which carry nerve impulses ten times faster than normal human nerves. Experiments have shown that a warning input from the anal cerci can be transmitted into leg movement in as little as 0.045 seconds, literally faster than a blink of the eye.
Good Roach - Bad Roach
In some areas of the world roaches could be considered beneficial. In tropical areas where these insects abound, roaches play a significant role in the recycling of decaying plant and animal matter. For example, in the Amazon jungles a single species of forest floor roach is estimated to contribute to 6% of the turn-over of decaying plant material. In addition these critters are extremely important in many food chains composing a significant part of the diet of carnivores such as birds, lizards, rats and other small mammals. It has also been documented that in many areas of the world some species of roaches are important as pollinators of certain rainforest plants. Actually some roaches, especially the tropical rainforest species, are quite beautiful (Figure 5). Because of their relatively large size and ease of rearing, roaches are the most commonly used specimens in studies of insect behavior, physiology, anatomy and morphology. Finally some of the larger species (and even smaller ones) have become quite popular as pets in the US and other countries such as Japan. A quick search of the web will reveal many sites that sell these seemingly disgusting critters.
Figure 5. Some rather striking tropical rainforest roaches. Images courtesy of Peter Chew
Although in some situations these insects could be considered beneficial, a recent survey conducted by the US Fish and Wildlife indicated that cockroaches were the least favorite animal in the US followed by mosquitoes, rats, wasps, rattlesnakes and bats. With many individuals the mere sight of a cockroach can bring on nausea. One of my recent students who was enrolled in a general education course in entomology indicated that she liked most of the pictures on a CD we used in the class, but that every time the picture of a roach appeared, she ran out of the room screaming.
This fear of roaches is without a doubt a learned response. Studies indicate that children under the age of 4 typically have no fear of roaches, but older children are typically told by their parents and peers that these critters are disgusting, vile and filthy. A personal note-our kids and grandkids have had repeated exposure to a colony of Madagascar hissing cockroaches that we have maintained for years. Not one of them considers roaches to be disgusting, vile or filthy. Of course from the standpoint of a pest control operator, the fear of roaches is not a bad thing.
The role of roaches in the transmission of disease is well-studied. Studies indicate that about 40 different pathogens are naturally carried by roaches, making them possible suspects in the transmission of diseases such as polio, leprosy, bubonic plague, dysentery, food poisoning, pneumonia, salmonella, typhoid fever and infectious hepatitis, among others.
Certainly the transmission of these diseases is not limited only to roaches. Water, air, hands, flies and any of a number of other ways can also transmit such maladies. Such transmission is referred to as mechanical, meaning that there is no biological association between the pathogen and vector. In the case of roaches transmission is quite simple. The pathogen is transferred from the source to the victim externally on the exoskeleton or parts of the insect. One of many possible scenarios could be a roach lives in a sewer and subsequently moves to human food, thereby moving the pathogen from the source to the food. Another possible means of transmission is through the feeding. When roaches feed they regurgitate partially digested food and frequently defecate near their meal. Again a simple scenario could be a roach feeds on feces (they seem to love it-check your dog feces in your backyard if you don’t believe it)) and then moves on to human food.
The role of roaches causing allergies or asthma is well-documented. According to the National Institute of Health, as many as fifteen million Americans may suffer from roach related allergies. There is additional evidence that roach related allergies may lead to allergic reactions when consuming other arthropods such as crabs, shrimp and lobsters. Such allergies are not due to the insects themselves but due to products of their presences such as feces, cast skins and pheromones. Typical symptoms of roach allergic reactions include runny nose (mild), rashes, labored breathing or in the most severe cases death from shock (rare). Roach allergies are more common in low-income neighborhoods (more roaches) and when people are crowded together under unsanitary conditions and in the northern areas with long winters where individuals are more confined to indoor situations.
Behavior and Biology
Cockroaches have flat oval bodies, elongate antennae and heads held so as not to be visible from above. Their front wings are leathery (tegmina) and may be well developed (macropterous), short (brachypterous) or lacking (apterous). In many species the female’s wings are shorter than the male’s.
Most common species of cockroaches lay their eggs in cases called ootheca (Figure 6). These structures differ drastically from species to species and species identification can readily be detected from the ootheca alone. Some species carry the ootheca until the nymphs are nearly ready to hatch; others may attach them to structures, while still others either drop them randomly or place them strategically in their environment. A few species retain the ootheca inside their body and give birth to living young when the eggs hatch (Figure 7).
Figure 6. A German cockroach with ootheca protruding from its abdomen.
Figure 7. First instar nymphs born alive with eggs hatching inside body.
Many of the roaches that are commonly found inside homes are positively thigmotactic, meaning that when at rest, they prefer to hide with a surface touching the top and bottom of their bodies (Figure 8). Of course this means that they typically hide in cracks and crevices. Most roaches are also negatively phototropic meaning they avoid light and are typically active at night.
Figure 8. American cockroach resting in a typical location-cracks and crevices.
Many species of cockroaches are also gregarious, frequently being found together in non-social groups. It is thought that they secrete pheromones that help them to congregate; thefunction of these loose groups is not totally understood.
Roaches are omnivorous (feeding on all types of food). These insects will eat almost everything humans eat and much more: to mention a few this includes feces, book bindings, paste, paper, cardboard, rotting tree stumps, bat guano, an assortment of living plant parts, other insects, corks on bottled wine, tobacco, ink, fish, leather and any rotting organic matter. Even though they can survive on a tremendous variety of food, experiments indicate that when given a choice, the common structure-inhabiting species are drawn to starches and sugary materials rather than to fat or meat.
Cockroaches have even been found feeding under the toenails and fingernails of patients confined to hospital beds. In some ocean freighters, the roach populations are so large that crew-members sometimes wear socks and gloves to bed to prevent cockroaches from feeding underneath their fingernails and toenails. There are also many records of roaches feeding on the skin of dead bodies (ok, that’s pretty gross). Typically, this looks like abrasions, chemical burns or even small pits. Additionally roaches may feed on human hair, sometimes removing entire shafts. There are some records of roaches even feeding on the eyelashes of living children.
As previously mentioned most species of roaches live outdoors and prefer a warm, humid environment. In the US only 5 species are commonly found in the habitats of humans and become major pests. These domestic species are the American cockroach (Periplanetia americana), the Oriental cockroach (Blatta orientalis), the brown-banded cockroach (Supella longipalpa), the German cockroach (Blatella germanica) and the smoky brown roach (Periplaneta fulginosa). All these species originated in the tropics and were introduced into the United States via commercial transport.
American Cockroach - Periplaneta Americana
This cockroach is the largest of the domestic species, with adults rarely reaching 1-1/2 inches in length. It is chestnut brown with light brown-to-yellow bands around the margin of the top of the prothorax (Figure 9).
Figure 9. A female American cockroach carrying the beginning of an egg case or ootheca.
This is the most common species of roach found in sewers in America, hence the common name sewer roach. Other common names are the palmetto bug and Bombay canary (in England). In much of Asia this is the most common roach found in homes, replacing the German roach, which is the most common species in homes in the US. In addition it frequently infests ships, large commercial buildings, food storage areas and basements.
In the US this roach is primarily an outdoor species but may enter homes to feed. Even so it is the least common of the 4 domestic roaches that are found in structures. The life cycle from egg to adult may require from 6 months to 2 years, passing through up to 13 nymphal stages or instars (Figure). As with all insects the length of development primarily depends on prevailing temperature. The warmer the temperature the faster an insect completes its life cycle. The American roach prefers temperatures above 70 F and high humidity with the optimum temperature for development around 80 F.
In addition, adults can live up to one year. During this time females can deposit 50 or more egg capsules, which contain up to 16 eggs each. Typically the first few ootheca a female produces contain the full compliment of 16 each but this number decreases in subsequently produced cases. Ootheca may be glued to structures, but more commonly are dropped in warm protected locations several hours after formation.
Oriental Cockroach - Blatta Orientalis
The adult Oriental cockroach is a large (about 1 1/4 inches long) shiny-black-to-reddish-brown species which exhibits sexual dimorphism (male and female of a species being distinctly different in form). The females (Figure 10) are nearly apterous with very short vestigial wings, while the males are brachypterous with the wings covering all but the last 2 abdominal segments. The female can be distinguished from last instar nymphs by the presence of veins in her vestigial wings.
Figure 10. An apterous female Oriental cockroach.
A brachypterous male Oriental cockroach.
This species, as well as some others, is frequently referred to as ’water bugs’ because many homeowners are reluctant to admit that they have cockroaches and also because this roach prefers humid environments. Another common name is the black beetle and in Hawaii they are referred to as Cyprus bugs. This is primarily an outdoor species, but is common in garages and will readily enter other structures at night to feed. The key environmental conditions for their presence are damp, dark locations. A common location for Oriental cockroaches is water meter holes in alleys. These cavities are dark, humid and undisturbed. The roaches emerge at night to feed in garbage cans, pet food dishes and on dog feces and rotting fruit in the yard. Rock walls, cement block fences and damp crawl spaces are other common locations. We have a large fig tree in our front yard next to a block wall fence. Because I am always looking for a food sources for the various reptiles we keep, these roaches are a good alternative source when I run out of purchased crickets. I am sure some of our neighbors think I am a little weird when they see me collecting Oriental cockroaches from the water meter holes in the alley. It is not uncommon to find several hundred roaches in one meter hole.
The life cycle of this species is quite similar to that of the American cockroach--completing one generation in as little as 6 months or taking as long as up to 2 years. This roach passes through 7 molts or nymphal instars, typically reaching adulthood in the summer and fall months in temperate areas.
The nymphal stage of the Oriental roach appears very similar to that of the American roach. Normally the oriental roach is much darker in color than the American. One morphological characteristic that can be used to make the distinction is the presence or absence of the white sticky pad found beneath the tarsi. The Oriental roach lacks these structures. This is the reason why a homeowner occasionally finds one of these roaches in the toilet, bathtub or sink. The roach will crawl down into these basins for water and then cannot climb back out due to the lack of the pads and slickness of the surface.
In colder areas the active populations tend to die out, passing the winter as ootheca located in warm protected locations. In the American roach, each ootheca contains up to 16 eggs each; however, unlike the former, which can produce up to 50 egg cases per female, the Oriental female only typically produces 2 to 7. Correspondingly, unlike the American adult roach, which can live up to 2 years, the Oriental adult only lives the few months necessary to produce her reduced number of ootheca.
Brown Banded Cockroach - Supella Longipalpa
The brown-banded cockroach is a smaller species, which is about l/2 inch long, brown in color and distinguished by horizontal tan stripes on the base of the wings behind the prothorax and across the middle of the first pair of leathery wings or tegmina. The sexes differ in that the male is longer, narrower and possesses fully developed wings, while the female is darker, broader and has shorter wings (Figure 11). Because the males and females look distinctly different, it is not uncommon for a homeowner to think they have an infestation of 2 different species. There is also quite a bit of variation in color from population to population ranging from decidedly black to pale tan.
Figure 11. A female brown banded cockroach.
Figure 11. A male brown banded cockroach.
This insect typically exhibits from 6 to 8 nymphal instars. These immatures are typically dark brown in color with a pale margin on the prothorax. Dorsally the remaining thoracic segments are pale in color and there is a pale brown band on the abdomen. The alternating dark brown and pale coloration makes the nymphs easy to recognize.
As with the German roach the brown banded roach is found in all US states with the possible exception of Alaska; however, it is not nearly as commonly found in homes and other structure as the German. In California it is estimated to occur in 5% as many homes as the German roach. This roach prefers high temperatures with optimum development occurring around 80 F. Since most homes typically are maintained at much lower temperatures it follows that this would be less than ideal for the brown banded roach. This species also has 25 % longer life cycle than the German roach ranging from approximately 100 to 200 days. When present the distribution of this roach in the home is throughout the structure. Male will readily fly when disturbed while the female will not.
The female carries the ootheca for 24 to 36 hours before gluing them to any of a variety of objects. Corners and under chairs and tables seem to be a common location but other possible location to mention a few include furniture, clothing, sinks, shelves, bedding, draperies and behind pictures. A female may produce up to 14 egg capsules with an average of 14 eggs per capsule. These are the smallest of ootheca produced by the domestic roaches and are typically found in clusters.
German Cockroach - Blatella Germanica
This is the primary cockroach found in homes and restaurants in the United States, with approximately 90% of roach infestations in structures attributed to this species. To say the least this is one of the bread and butter insects of the structural pest control industry attributing to a large part of their business. This roach is about the same size and color as the brown-banded, but can readily be distinguished by 2 longitudinal black stripes on the dorsal side of the prothorax (Figure 14). There are minor differences in the overall appearance of the males and females of this species. The female is typically darker and has a broader abdomen than the male. In the nymphal forms (Figure 12), the stripes extend down the thorax and abdomen.
Figure 12. German roach illustrating 2 longitudinal stripes on the prothorax.
The German cockroach is unique in that the female carries its ootheca protruding from the abdomen until the eggs are ready to hatch. This is to our advantage when attempting to eradicate this pest from our homes. If a female carrying an egg case is killed, the unhatched eggs also die. The egg case of the German cockroach is relatively thin walled and will quickly dehydrate if removed from the female prior to the point where it is released naturally. Apparently the female provides an essential amount of water to prevent desiccation of the case. Eggs of most insects are difficult to kill with pesticides. Unfortunately, the American and Oriental cockroaches drop or glue their egg cases to structures soon after they are formed. The brown-banded cockroach attaches them behind objects, such as drawers and picture frames.
The German cockroach has a faster life-cycle and lays more eggs than any of the other common house-infesting roaches. As a consequence it tends to increase in numbers more rapidly than these species. Under ideal conditions this insect can produce 3 to 4 generations per year. In addition each female can produce up to 8 ootheca which can contain 30 to 40 eggs each. Their reproductive capacity plus the fact that the environmental conditions that are typically found indoors are ideal for their development leads to their major pest status.
A simple comparison of the potential reproductive capacity of the German and Oriental cockroach (or actually any of the other pest species) will illustrate the difference of each. On average a female Oriental cockroach produces 5 egg cases containing 16 eggs each and after hatching, the nymphs require a year to grow to adulthood. A simple calculation indicates (assuming 100% survival) that a mated female Oriental cockroach is capable of producing 80 adult roaches in a one-year period. On the other hand a female German cockroach produces an average of 8 egg cases containing 16 eggs each, which after hatching complete development in 3 months. As a result after 3 months one female would produce 108 adults, half of which are female. In turn those females would produce 5832 adults in another 3 months. Assuming 2 more generations after one year, a single female German roach is capable of indirectly producing 17, 006,112 offspring or 212,576 times as many offspring as the female Oriental roach. It should be emphasized that this is a hypothetical calculation and there are many factors that greatly reduce the reproductive capacity of roaches, but it does give great insight as to why the German roach is so much more of a pest than the other domestic species.
During the 1950’s and 60’s, if a home was infested with German cockroaches, they were almost exclusively confined to kitchens and bathrooms. Over time, infestation gradually began to be seen in different areas of the home; today they frequently are spread throughout the structure. This apparent change in cockroach behavior can be explained by a combination of changes in human behavior and home construction since the 1950’s.
German cockroaches prefer environments with high humidity, moderate temperature and available food. Thirty years ago the family normally sat and ate dinner and other meals together in the kitchen. Today, due to busy schedules, two-income families, and the advent of television and computers, families rarely eat meals altogether or in the kitchen. Consequently, crumbs and other droppings are spread throughout the home and attract these roaches. Higher humidity in the 1950’s was typically confined to the bathroom and kitchen and older homes were usually built with one bathroom. However, bathrooms in newer homes frequently are found in several areas. As a consequence, there is increased humidity throughout the structure. Also, with the advent of central air conditioning, moisture tends to condense in wall voids where the cool room air meets the hotter outdoor air. Finally, there has been a tremendous increase in the number of televisions, computers and other small appliances in homes; these are sources of heat that attract German roaches. Additionally, while sitting for long periods at the computer or television, we often have a little snack (or a full-blown meal). The combination of heat and food must be irresistible to cockroaches!
As with other species German cockroaches tend to be gregarious--meaning they are often found together in clusters in aggregates. Favorite locations typically occur on porous substrates like wood or paper and where it is moist, dark and with readily available food. The clustering of roaches is due to an aggregation pheromone that is produced in their feces. This chemical is very attractive to both the adults and nymphs. Examples of these locations include stacks of paper bag, cracks and crevices around cabinets, wall and ceiling voids and in and around refrigerators, dishwashers, stoves, dryers and water heaters.
German cockroaches can reach tremendous populations in a fairly short period of time when the right conditions exist. Recently, there have been a number of lawsuits throughout the U.S. where tenants are suing slumlords for continuous unsanitary and run down conditions. Large rat and German cockroach infestations are a considerable part of the problem. In some cases the tenants have actually won the apartment complexes as part of the settlement.
The authors recently visited one of these heavily infested complexes in Los Angeles. Upon entering one of the units, we noticed over a hundred roaches that were sitting or running about on the walls. This was quite unusual because it was daytime and roaches, of course, are nocturnal. Normally, in structures where roaches are active during daylight hours, it is an indication of a very large infestation as they probably have run out of places to hide. The tenant indicated that conditions had become intolerable: a bowl of food could not be placed on the kitchen table without it being visited by hoards of roaches. On several occasions roaches were found hiding in the ears and up the noses of sleeping children. The ultimate insult was when one of the tenants was feeding her two-year-old and a roach crawled out of the child’s mouth.
If that story grosses you out, I suggest you not read the rest of this paragraph. Recently a doctor friend was examining an extremely overweight lady. She claims that she was examining an area between two flaps of fat on the patient’s arm. She first found cookie crumbs and then a few German cockroaches living in this and several other areas of the woman’s body. The doctor was repelled by the finding and required the patient to take a shower before continuing the examination. Although I am sure this is exceedingly rare, it does make biological sense. Such a situation meets all the biological requirement of this species: food, heat, high humidity and a thigmotactic location. (And a nice soft place for an insect to lay its head at night.)
Field Cockroach - Blatella Vega
This roach is very similar in appearance to the German and Asian cockroaches but can be distinguished from these by a dark area located on the face between the base of the mouthparts and the eyes. This species is also slightly smaller and more greenish-brown in color than the German roach. As with the German and Asian roaches there are 2 black parallel bars running the length of the pronotum (top of the prothorax) (Figure 13).
The field roach was introduced from Asia into California, Arizona, New Mexico and Texas. Unlike the German roach, thisspecies is not repelled by light and is often active during the daytime. It is most commonly found in irrigated areas southern Arizona and adjacent areas of California feeding mainly on decaying vegetation. Although primarily a field insect it may enter homes during dryer months in search of water.
Figure 13. A field cockroach, Blatella vega.
Because this species is closely related to the German roach it follows that it has a similar biology. Their life cycle can be completed in about 3 months and the ootheca is carried by the female until close to hatching. As with the German, if the capsule is removed or the female dies prior to this period, the nymphs will not hatch.
Australian Cockroach - Periplaneta Australasiae
The Australian cockroach closely resembles the American cockroach, but can be separated from the latter by its slightly smaller size (over one inch), the yellow margin on the thorax, and the light yellow streaks on the sides at the base of the wings or tegmina (Figure 14). It is about 1 1/4 to 1 3/8 inches long and the wings of both sexes cover the abdomen. The female has a broader abdomen than the male and lacks styli (peglike structures located between the anal cerci). Late instar nymphs possess distinct bright yellow spots along the margins of their abdomen (Figure 18).
Figure 14. Adult and nymphal Australian cockroaches.
This worldwide species has become established outdoors in the southern U.S. and in many greenhouses. In the United States it is most abundant in Florida, the costal southern states and in California it ranges as far north as San Francisco. Like the smoky brown roach it is found most commonly around the perimeter of homes and in southern Florida it is the most common outdoor species. Australian cockroaches are prevalent in leaf litter, in and around shrubs, flowers and trees, tree holes, woodpiles, garages, crawl spaces, attics, and greenhouses. It is a pest when it enters homes where it may eat holes in clothing and feed upon book covers. It is apparently more vegetarian than the others, and in the northern U.S., it has appeared in greenhouses and temporarily become a damaging pest.
The Australian cockroach life cycle requires about one year from egg to adult. The ootheca takes 40 days to hatch. There are 24 eggs per egg capsule, 16 of which hatch. Each female produces 20 to 30 egg cases. Nymphs take about one year to develop. Some parthenogenetic eggs hatch, but the nymphs do not mature.
Smoky Brown Cockroach - Periplanetia Fuliginosa
This species is similar to the American cockroach in size and shape (rarely reaching 1 1/2 inches in length) but is a uniformly dark brown mahogany color (Figure 15). The nymphs are also dark brown in color with white tips on the antennae in early instars and white basal segment in later instars. These roaches are primarily found in the Gulf States from central Texas to Florida and in Georgia, Southern California and North South Carolina.
The ootheca are large, dark brown, average of 17 eggs per capsule and are typically can be found glued to objects in their environment. The entire life cycle typically takes about 1 year to complete with nymphs hatching in the summer months. There is normally a large die off of the adults during the fall and winter months, especially in cooler areas.
This is primarily an outdoor species requiring a high moisture content to survive. They mainly feed on plants but in the absence of plants will feed on any of a variety of household foods. Populations build up outdoors but readily enter homes under doors, through garages or into attics as they are frequently found in gutters clogged with leaves and under roof shingles.
Figure 15. A smoky brown cockroach life cycle.
Exotic Non-Pest Species
Madagascar Hissing Cockroach
The Madagascar hissing cockroach (Figure 16) is an African species that has gained considerable notoriety due to its use in a number of movies (e.g. Damnation Alley, Indiana Jones and the Temple of Doom, Men in Black). In recent years they are regularly consumed on participant of Fear Factor. Adults may approach 3 inches in length and are capable of producing a hissing sound when disturbed. Contracting the body and expelling air out the trachea (internal breathing tubes) through the slit-like spiracles produces this noise. This hiss mimics that of a snake and is a startle-defensive mechanism possibly used to ward off attacking predators.
The effectiveness of this defensive mechanism was recently documented in our own home. I brought a box of hissing roaches home from school several years ago. They escaped by pushing open the lid of the box. I assured my wife that they were a tropical species and would not survive in our home. I was proven wrong 2 years later when we turned over our round oak table and there was a mother and her babies living in the hollow pedestal. Since then, one summer night a loud hissing in the front room wakened us. Upon inspection, our cat was sneaking up on a large roach, only to jump several feet in the air after the pounce of the cat and resultant hiss of a Madagascar roach.
Male hissers hiss for 3 additional reasons--all are associated with their mating rituals. These include-during aggressive encounters with other males, throughout courtship and while copulating. In one experiment the spiracles of male roaches were sealed preventing the ability to hiss. When placed with females these individuals were no longer attractive to females until the sound of hissing roaches was reproduced with a tape player.
Many schools have laboratory colonies of this cockroach because the U. S. Department of Agriculture has been quite generous in issuing permits for obtaining these insects. Hissing roaches have a long life cycle, under warm conditions requiring several months to complete development. The first instar nymphs are born alive as the eggs hatch inside the female. Males differ from females in that they are distinctly smaller than the latter and have a pair of short flat horn-like projections on the top of the prothorax. Like most species of roaches, they are omnivorous and seem to do well in captivity when fed dried dog food, vegetables and fruits. It should be noted that these are great escape artists and an aquarium with a very tight lid (no gaps thicker than a razor blade) is required to prevent their release.
Figure 16. Female Madagascar hissing cockroaches.
Figure 16. Male Madascar hissing cockroach.
Figure 16. They breed quite rapidly in captivity.
This (Figure 17) is certainly one of the largest species of cockroaches in the world, perhaps the largest. Their distribution is limited to northern Queensland and reaches a length of 3 1/2 inches and a weight of 30 grams (the weight of 2 sparrows). This is a burrowing species that forms permanent tunnels in sandy soil that may reach a depth of several feet. They emerge at night to feed on dried leaves that they frequently drag into their tunnels. As with hissing roaches the young are born alive. They have a very long life cycle and require up to 7 years to reach adulthood.
Figure 20. A giant rhinoceros cockroach.
In Australia they are frequently kept as pets and can be purchased in some pet stores where they are known as macrodogs. They have not reached the pet trade in the US to any extent as it is illegal to export any insects (dead or alive) from Australia. Of course there are always some exceptions to the rule. In this case if insects are captive bred they can be exported.
As with some of the larger insects they are being bred in captivity in Japan and are sold for several hundred dollars each in that country. Insects as pets in Japan have become very popular. I am sure part of the reason is due to the lack of living space and insects take up very little space. In many cases these insect pets sell for very high prices. I had a friend who was doing some work for National Geographic and ran across a new subspecies of a common rhinoceros beetle. He managed to collect 20 pair and brought them back to Japan and sold them to an insect breeder for $10,000 a pair in one day.
Typically cockroach infestations do not appear in the home or other structures on their own. In some situations the Oriental, smoky brown, American and other predominately outdoor inhabiting species of cockroaches may move indoors on their own. On the other hand, the German and brown-banded roaches are nearly always brought into homes by human activity. There are some records of German roaches mass migrating from one structure to another but this is extremely rare. Once established, roaches have the potential to breed to huge numbers in a relatively short amount of time. As mentioned one female German cockroach and her offspring have the potential of producing over a million new roaches after 3 short generations. Obviously this potential is never reached or we would be literally swimming in cockroaches. A number of factors limit this potential including natural mortality, available space, predators and parasites, availability of food and water and prevailing temperatures and humidity to name a few.
The presence or absence of these factors becomes very important in cockroach control. All structures have a limited capacity (carrying capacity) to support a certain number of cockroaches. Biological factors attempt to keep an insect population at that level, regardless of measures taken to reduce the population, like pesticide applications. For example when a number of cockroaches die after an insecticide application, the reproductive rate of the remaining roaches will increase to replace those individuals and keep the population near the carrying capacity.
An important phase of cockroach control is to attempt to reduce the carrying capacity of an infested structure. In some cases the pest control operator will not be able to accomplish this on his or her own, but he or she can educate the client and thereby increase the chance of successful control.
The most important factors that can be controlled to reduce the carrying capacity of a structure are the availability of food, water and space. A very small amount of water (much less than a drop) is all that is needed to maintain a cockroach for weeks, if not months. Any source will suffice including condensation on pipes, small leaks, moist sponges, soaked wood or even moist food. Cockroaches eat almost anything, including: crumbs, hair, fingernail clippings, feces, paper, spots of grease, oiled clothes, pet fur and dead insects (even dead cockroaches). They will cannibalize their own young and egg cases if food becomes scarce. Food high in protein or containing significant moisture content is very attractive to cockroaches. However, if forced to feed on less nutritious food such as wood, soap fingernails etc. their natural mortality rate will increase.
As previous discussed, domestic roaches are positively thigmotactic meaning they hide during the day where they have a surface touching the top and bottom of their bodies. This normally equates to crack and crevices that are around 1/16th inch wide. They also prefer to sit on wood and paper rather than metal surfaces. Their flat body allows them to squeeze into places where they can touch the surfaces above and below at the same time. Additionally the warmth around motors of dishwashers and refrigerators is attractive, especially if there is a drip pan under the refrigerator which provides water. In summary, one of the aims of a successful pest control program should include the reducing the availability of those factors (discussed above) that determine the carrying capacity of a structure.
Limiting the Availability of Water
Of the factors discussed above this is probably the most important in reducing cockroach populations. As with humans roaches can survive much longer without food than they can in the absence of water.
Plumbing is one of the most common sources of water for these insects. Any leaking faucets including the gasket at the base should be repaired. Normally if a faucet leaks at the base this occurs when the water us running. Roaches commonly crawl up into faucets for water so the screen that breaks the flow of the water into a steady stream should be in place. The plumbing underneath the sink, especially when the water is off, should be checked for leaks and repaired. A whitish residue around these pipes indicates a slow leak.
Pipe insulation may be needed to prevent cold water pipes from sweating during humid conditions in the summer. There is enough moisture on sweating pipes to sustain a sizable cockroach infestation. The insulation should be sealed to prevent roaches from hiding between the insulation and the pipes. All drains should be covered with a fine mesh screen. Most kitchen sink strainers will not keep cockroaches from going down the drain for moisture.
Other Water Sources
Damp dishrags or sponges are an ideal source of moisture and even bits of food. These can be rinsed with a mild ammonia solution or placed in a plastic bag. Potted plant dishes with standing water or even moist soil in plant pots can be a source of moisture. A layer of gravel over the soil will eliminate the latter sources. Other sources of water could include pet water dishes and refrigerator pans.
Limiting Food Supply
Sanitation start with a through clean up of the cooking area. This starts with cleaning behind and under the stove, refrigerator and freezer, if present. The outside of the appliances should also be cleaned. A tremendous amount of food refuse accumulates under the stovetop. Particular attention should be paid to any accumulation of grease which is roach caviar. Cockroaches readily feed on the film of grease on oven hoods and walls next to or behind where frying pans, or grills are used.
When possible foods should be stored in cockroach proof containers. This isn’t as simple as it seems as these beasts can chew their way through most types of packaging including thin soft plastic, aluminum foil, paper and cardboard. No open food should be left out overnight, especially on dirty dishes in the sink. It is difficult to completely deprive cockroaches of a food source, but limiting food resources makes it easier for other control methods to work effectively.
Unlike humans roaches make no distinction between garbage and a gourmet meal. A garbage disposal is very helpful in reducing waste in the home. However, the garbage disposal must be used daily or whenever waste is deposited, and it should be flushed thoroughly after each use. If a top cover to the drain leading to the disposal is available this should be in place when not in use. All food preparation surfaces, pots and pans and dishes should be thoroughly cleaned as soon as possible after eating but certainly before retiring.
Eliminating Hiding Places
Keep in mind roaches prefer to be in tight, small places and to rest on porous surfaces such as wood, cloth and paper. Stainless steel, aluminum, plastic laminates, ceramic tiles or baked enamel surfaces are less preferred for resting. When these "soft" materials are layered (such as corrugated cardboard), it forms an ideal site for cockroach resting and breeding. Do not keep paper bags, sacks, cardboard boxes, rags or pieces of wood in locations where cockroaches may be present. One of the biggest mistakes is to store paper sacks next to the refrigerator because it provides a layering effect next to a warm area and high source of humidity. Equally troublesome is the storing of paper bags in layers in kitchen drawers.
Ideally narrow cracks, seams and crevices should be sealed in order to reduce the hiding places of roaches. Frequent hiding places include behind molding, small holes, around rubber gaskets on refrigerators and freezers, in seems beneath kitchen tables and where cabinets or walls meet, or around built-in appliances. Caulking is the most commonly used method to seal most of cockroach hiding places. Of the various types available silicone caulks are preferred as they do not shrink, crack and cannot be chewed through by roaches.
Inspecting For Infestations
The first consideration in inspecting for a cockroach infestation is to identify the roach or roaches you are dealing with. Once identified then the knowledgeable operator will have a better idea as to where he or she would likely find the roaches. For example German roaches and brown banded roaches may be spread throughout the house and Oriental and American roaches are more likely to be found outdoors or in warm moist situations in the home. One of the chief tools is a good flashlight, which is needed to examine those hidden dark locations where roaches are likely to occur. Also a long handles mirror may be of use in checking those hard to reach locations.
There are a variety of sticky traps that are available which can be used to determine the extent and size of the infestation but have limited use in determining where the roaches are hiding. A number of aerosol products are available which have a flushing action and are very useful in driving roaches out of their daytime hiding places.
Chemical Control Formulations
When selecting a pesticide for any type of control, an important part of the process is choosing the right formulation of the product. A pesticide chemical can rarely be used as originally manufactured. The pesticide must be diluted with water, oil, air or chemically inactive (inert) ingredient so that it can be handled by application equipment and spread evenly over the area to be treated. Usually the basic chemical cannot be added directly to water, so the manufacturer must further modify his product by combining it with other materials such as solvents, wetting agents, stickers, powders, or granules. The final product is called a pesticide formulation and is ready for use either as packaged or diluted with water or other carriers.
Different formulations can be a very important component of the desired end result. Formulations can affect not only how well the product kills the target organism (cockroaches in this case) but will also affect the relative safety, visibility, relative active length of the residue and presence or absence of odor of the product. Other considerations in making a choice include affect on application equipment, danger of drift and runoff and possible injury to surfaces. Generally speaking in structural pest control and with cockroaches a desirable product would usually have a long, odorless and invisible active residue that is inexpensive and relatively safe to non-target organisms (humans, pets, fish, etc.).
The types of formulations that are commonly used in structural pest control are wettable powders, emulsifiable concentrates, microencapsulated materials, dusts, baits, aerosols, flowable powders, solutions, fumigants and a variety of specialized formulations.
Aerosols-A (Pressurized Cans)
These contain a small amount of pesticide, or a combination of pesticides. When contents of the can are forced through a small opening in the cap by pressure created from an inactive gas, very fine droplets are produced. Aerosols have a long shelf life remaining active in the formulated form for a relatively long time. They are only practical for use in small areas since there is only a small amount of chemical in the typical canister making them relatively expensive. In addition since the droplets in the spray are so small they tend to drift and can end up in unwanted locations. Aerosols can be dangerous if punctured or overheated. Finally children tend to play with aerosol cans making them inherently hazardous.
Dusts are formulate by atomizing on or mixing in a low concentration of a pesticide with a finely ground inert carrier such as talc, clay, or volcanic ash. There typically is a wide range in size of the dust particles in any one formulation. Dusts are ready to use as purchased and require no mixing and can be applied with simple, lightweight equipment even in commercial use. On the other hand they tend to be abrasive to application equipment.
Because dust particles are finely ground, they may drift long distances from the treated area and may contaminate off-target areas. Their residue is highly visible, a very undesirable trait in most structural situations. When used outside, they are easily dislodged from the treated surface by wind and rain and soon become inactive.
Because of drift, dusts are not recommended for large scale outside use. Outside they are used principally for spot treatments and home gardens. Inside, they are used in cracks and crevices for roaches and other domestic insects.
As their name implies baits are formulate by mixing a pesticide with an attractive food which when consumed kills the pest species. They are useful for controlling pests such as flies, rats, mice, squirrels, cockroaches and ants that range over a large area. Often the whole area doesn’t need to be treated, just those spots where the pests gather. Usually only small amounts of pesticides are used in comparison to the total area treated, so potential environmental pollution is minimized.
Many of the newer baits that are used for roach control are very slow acting and once consumed may take a few days to kill. This actually can work to the advantage of the pest control operator. This is especially true with the German cockroach. Their use may result in what is referred to as the domino effect. With the German roach and probably other species, the first instar nymphs typically do not forage for food and remain in cracks and crevices to feed on what is available. Typically most of this food is the feces to the older roaches which have been foraging since roaches tend to defecate in their harborages (hiding locations). This feces is quite high in proteins, other nutrients and even cockroach bait if this has been consumed by the foraging forms. As a consequence not only the foraging forms are killed but so are the first instar nymphs which otherwise may be difficult to locate and kill with conventional sprays
Within the home, some baits are often attractive and dangerous to children or pets and therefore must be used with care. Outside, they may kill domestic animals and wildlife as well as the pest. Often the pest will prefer the protected crop or food rather than the bait or in the case of household pest they may prefer other foods so the bait may be ineffective.
This type of formulation is typically a solution consisting of a low concentration of the active ingredient (toxicant) dissolved in highly refined oil. As their name implies they are typically used and sold with no mixing necessary. Because mixing is not needed there is less of a chance of making mistakes. Formulations typically lack unpleasant odors and the liquid carrier evaporates quickly and does not stain fabrics, furniture, etc.
Emulsifiable Concentrates (EC)
These formulations are prepared dissolving the toxicant (active ingredient) in a solvent and adding an emulsifying agent. When the formulation is mixed with water an emulsion is formed. In an emulsion small droplets of the formulation are suspended throughout the water carrier giving it a milky appearance. The emulsifying agent basically allows the oil droplets to suspend in rather than separate in a layer from the water. Other ingredients possibly include wetting agents, stickers, and other additives. As their name implies these are concentrated formulations and may contain eight or more pounds of active ingredients per gallon of concentrate.
These formulations contain a high concentration of pesticide, so the price per pound of active ingredient is rather low. Only moderate agitation is required in the tank, so they are especially suitable for low -pressure, low-volume weed sprayers, mist blowers, and small home ground sprayers. Emulsifiable concentrates are not abrasive and do not settle out when the sprayer is not running. There is little visible residue, which generally allows their use in populated areas. Because of the high pesticide content, the applicator is not required to store, transport, or handle a large bulk of chemical for a particular job.
Since they contain such a high concentration of active ingredients mistakes in mixing are enhanced as is the hazard to the applicator, especially since many are readily absorbed through the skin. Because of their solvents, most liquid concentrates cause rubber hoses, gaskets, and pump parts to deteriorate rapidly unless they are made of neoprene rubber. Some formulations cause pitting in car finishes.
Wettable Powders (WP)
Wettable powders formulations containing a relatively high concentration of pesticides. The toxicant is sprayed on or mixed with a dust carried. A wetting agent is included in order to allow the dust to suspend in water. As is true with liquid concentrates, the pesticides in wettable powders are relatively low in cost and easy to store, transport, and handle. They are safer to use on tender foliage and usually do not absorb through the skin as rapidly as liquid concentrates. They are easily measured and mixed when preparing spray suspensions.
Wettable powders may be hazardous to the applicator if he inhales their concentrated dust while mixing. They require good agitation (usually mechanical) in the sprayer tank and will settle quickly if the sprayer is turned off. They cause some pumps to wear out quickly. Their residues are more visible than other formulations.
These are formulated by wrapping the toxicant in a tiny polymer capsule that is small enough to pass through a spray nozzle. Additional ingredients are added to allow the capsules to suspend in water and adhere to various surfaces including insects. As the capsules begin to slowly degenerate the toxicant is released. Microencapsulation greatly changes the characteristic of a toxicant. The mammalian toxicity is greatly reduced. If ingested the capsules will pass through the mammalian digestive system without releasing significant toxicant. Also since the microcapsules degenerate very slowly the residual activity of the pesticide is greatly increased.
Products Available For Cockroach Control
It should be noted that this discussion is not a recommendation of any product and that all products discussed below may not be available for legal use in some states.
There are basically nine groups of pesticide chemicals and most contain several products that can or have in the past been used for cockroach control. These groups are the
- Chlorinated Hydrocarbons
- Organophosphate Compounds
- Synthetic Pyrethroids
- Phenyl Pyrazoles
- Growth Regulators and Baits, Metabolic Poison
- Fumigants and Miscellaneous Compounds
This group includes those chemicals that lack carbon in their molecular structure. Almost all are naturally occurring, slow acting, relatively nontoxic to mammals including humans and relatively inexpensive. The most commonly used inorganic pesticide for roach control is boric acid which is sold under a variety of brand names including Boric Acid, Borid, and Permadust. This pesticide has two primary modes of action. It is a desiccant and works by abrading or wearing off the epicuticle or waxy layer that is on the outside of the insect’s exoskeleton. As previously discussed the epicuticle functions to prevent excessive amounts of water evaporating from the insect. If worn off the insect basically dies from dehydration. Also if ingested boric acid as will cause a blockage in the insects digestive system which eventually results in death.
This chemical has a tremendous residual activity remaining active for the better part of a year and is relative safe to use with an acute oral LD50 between 2.000 to 4,000. It has a very visible residue but is quite suitable for treatment in those places where this isn’t a problem. It is essential to use this material in areas where excessive moisture is not a problem.
A number of these chemicals were once widely used in structural pest control but because of a number of unwanted side-effects they have been phased out for all intents and purposes; there are some minor exceptions but none are used for roach control. Included in this group are the following:
Many plants contain naturally occurring insecticides. These function to prevent insects from feeding upon them. The only botanical insecticide that is used in structural pest control is pyrethrin. This chemical occurs in chrysanthemum flower heads and is extracted commercially in Kenya, Africa. The process from growing the flowers to extraction and then further refinement is quite complicated and time consuming. In addition pyrethrin is a weak insecticide and requires a fairly high concentration to kill insects. As a result of both of these factors pyrethrin is relatively expensive. Even so it has found its way into a number of types of pest control due to some unique characteristics. In lower concentrations it has a flushing effect causing cockroaches and other insects to become very active and leave their daytime hiding places. As a result it is used to check for cockroach infestations. A simple crack and crevice treatment will quickly determine the exten of an infestation or success of prior treatment. It is also used in combination with other chemicals. It can be fogged to excite roaches and drive them over residues of stronger chemicals. Another advantage of this chemical is that it has a very short residue and can be used in situations wher long residual activity may be a problem.
Finally pyrethrin produces a quick knock-down, almost instantly paralyzing insects. For this reason it has been used in some household aerosol products. This is a big selling point to the homeowner if he or she can immediately see the treated insect die. Unfortunately unless high concentrations are used the treated insect is only paralyzed for a short amount of time. As a result other cheap chemicals are frequently added to these aerosols to kill the critters a little later.
- Pyrethrins Products: aerosols, PT-565, PI, CB-80 Extra
- Purge Products: Liquid Concentrates, BP-300, MGK 3%, Exciter, Drione, Aero-Cide and Kicker.
The organophosphates (OPs) were developed as a replacement for the chlorinated hydrocarbons. Many are quite toxic to humans and therefore are not acceptable for structural pest control but have found their way into agriculture. A few were acceptable for structural pest control and have been used for many years. These are discussed below but in most cases have been replaced by some of the newer pesticides for cockroach control.
Products are Dursban Pro, Killmaster. EPA registration of most products containing this chemical is apparently in the process of cancellation or have been cancelled.
Products are Diazinon 4E, Knox-out 2FM. This is a widely used slow acting pesticide and is mostly used outdoors due strong odor. It can be used as a perimeter treatment. Knox-out is a microencapsulated formulation which can be used for crack and crevice treatment with little odor, a low mammalian toxicity and long residue.
Product is Catalyst. Effective against cockroaches, mosquitoes and fleas.
Procuct is Orthene PCO. Effective against roaches & other pest inside structures. An excellent rotation material, which can be used as an alternative to the pyrethroids in an attempt to slow down pesticide resistance.
This group of insecticides was developed in the late 60s slightly after the organophosphates. They typically have a longer residuals and lower mammalian toxicity the OPs.
Products are Baygon bait, Baygon WP-for roach control it is mainly used in household aerosols.
Product is Sevin SL. This chemical has a wide registration and is used for many purposes. It is an inexpensive product but has limited use for roach control since new and more effective materials are available.
This is a fairly new group of chemical that are sometimes referred to as the synthetic pyrethroids. The name refers to the fact that unlike their name sake pyrethrtin, they are synthetically produced.
Most are relatively safe to humans, inexpensive, very heat stable, quite toxic to fish and vary in effectiveness depending on the surface to which they are applied (e.g. greasy or oily surfaces tremendously reduce their effectiveness).
Products are Dragnet FT, Prelude-both materials are used as insecticides & termiticides.
Products are Cynoff WP & EC, Demon WP & EC, Prevail TC, 4th generation. These materials are also used as insecticides & termiticides in the pest control industry.
Products are Tempo 20WP, Intruder HPX, CY-KICK CS, OPTEM. This active ingredient was formulated specifically for the use of commercial restaurant, USDA facilities, Poultry farms & other sensitive buildings serving or producing foods.
A product is Talstar Flo. This active ingredient was also formulated for general pest control and termite control.
Product is Demand CS. This is one of the newer materials. It is microencapsulated and therefore has a long residual and is less hazardous to humans. It can be used outside & inside including restaurants and sensitive areas such as USDA plants & A.I.B. Facilities.
Products are Suspend SC, Delta Dust. Worldwide this material is number one in agriculture. In addition it is used in general pest control as an outside perimetertreatment and inside treatment including a label also for restaurants. When the dust formulation is used inside wall void or other enclosed situations it may remain active for up to 2 years.
Product is Vectrin 3%. This material is specifically used as a concentrate space spray for roaches inside restaurants and other sensitive areas. It has a relatively short residual but longer than the botanicals (pyrethrum).
This is a new group of pesticides. They are relatively slow acting slow, but very effective on termites & roaches. This material mimics the chloronated hydrocarbons on effectiveness.
- not a cholinesterase inhibitor
- very effective material when used in small amounts
- LD 50 when mixed is greater than 5,000 with a caution label, no skin or eye irritation