Of the 69 species of cockroaches established in the United States, most live outdoors in feral or peridomestic habitats. Sometimes, these species enter residences and become household pests. The use of firewood and live plant material indoors, along with the movement of large numbers of people to the suburbs, enhances the chance of peridomestic species invading homes. Exterior landscaping with natural flora, trees and shrubs creates the ideal habitat for peridomestic cockroaches that thrive in treeholes and leaf litter.
FAMILY BLATTELLIDAE FIELD COCKROACH
Blattella vaga Hebard
The field cockroach was likely introduced from Asia into Southern California, Arizona, New Mexico and Texas. It is very similar in appearance to Blattella germanica (Linnaeus) but can be distinguished by the blackish/brown area on the face from mouthparts to between the eyes and by its slightly smaller size and olive-brown coloration. This cockroach, unlike the German cockroach, is not repelled by light and can often be seen during the day. It is common in irrigated regions of southern Arizona and adjacent areas in Southern California. Blattella vaga is known in Arizona, California and Texas.
Field cockroaches feed largely on decomposing vegetation and occur under stones, clumps of earth, debris and similar objects. Unlike most other species, field cockroaches are not gregarious and rarely enter buildings. They are actually repelled by their own conditioned filter paper and do not respond to paper conditioned by other species.
During drier parts of the year, the field cockroach may enter structures in search of moisture. Control can be achieved by removing decomposing plant material from around the home. Spray the foundation area, edges of lawn, outdoor flower boxes and similar areas where moisture collects with a water base spray.
Blattella asahinai Mizukubo
The Asian cockroach was first collected in North America in Kathleen, Fla., in 1986. At the time of the discovery, this species was well established and was probably introduced into North America via the port of Tampa (Florida) at least a few years earlier. Since then, it has been detected in most parts of Florida and has the potential to extend its range over a wide area of the southern United States. For practical purposes, the Asian cockroach is identical in appearance to the German cockroach. Even the experts have difficulty determining whether a dead specimen is Asian or German.
The behavior of the Asian cockroach is different from the German cockroach. The Asian cockroach is an accomplished flier and lives outdoors in feral and peridomestic habitats. The Asian cockroach can invade homes and become established. At dusk, this species becomes very active and adults are attracted to light reflected off light-colored walls, doorways and windows. When lights are turned off as residents leave a room, the cockroaches will follow to the next lighted room. Thus, many residents may believe that these cockroaches are "attacking" them.
The Asian cockroach is susceptible to all commonly used insecticides. Because only a few Asian cockroaches enter a house at night, indoor applications of insecticides have been completely ineffective for control. Several scatter baits have been developed for control of Asian cockroaches and have provided successful control of populations.
PENNSYLVANIA WOOD COCKROACH
Parcoblatta pennsylvanica (DeGeer)
Twelve species of Parcoblatta are found in North America, with most occurring in eastern locations. Some have been identified as occasional invaders. Only two species, P. americana and P. notha, are found in the regions of the Pacific Northwest or Southwest. The Pennsylvania wood cockroach is one of the most commonly sighted species of Parcoblatta in urban and rural environments.
Pennsylvania wood cockroaches also occur at significantly greater heights than the other Parcoblatta species, as they prefer less exposed areas such as under bark, in rotting logs and in dense undergrowth.
The male of this species is one inch (25 mm) and the female is 3/4 inch (19 mm) in length. The coloration is light to dark brown with a lighter-colored band bordering the lateral margins of the forewings and pronotum. The two sexes differ so greatly in appearance that they once were described as separate species. The woods cockroach, P. virginica, is a related species widely distributed in the eastern, southern and midwestern states, up into Canada. The Pennsylvania wood cockroach is usually found in hollow trees, under loose bark and often in wood piles and in crevices in rural buildings.
The use of firewood, the popularity of cedar shake shingles and the building of homes in wooded areas increase the likelihood of encounters with species of Parco-blatta. Control efforts should focus initially on habitat alteration before insecticide treatment is considered.
Physical procedures such as moving wood piles away from buildings, screening windows and strategically redirecting exterior lighting can reduce the potential for Parcoblatta species finding their way indoors. Perimeter applications of residual sprays or granular insecticides are useful in managing large exterior populations. Although Pennsylvania wood cockroaches are not likely to reproduce indoors, fast-acting residual or nonresidual insecticides may be needed to quickly eliminate established indoor populations.
LITTLE GEM COCKROACH
Euthlastoblatta gemma Hebard
The "little gem" or "short-wing gem" cockroach resembles the brown-banded cockroach, but it has vestigial (rudimentary) wings.
It most commonly inhabits crevices in tree trunks and similar outdoor harborages in the Gulf Coast states and into South Carolina.
It has also been found residing behind signs nailed to trees and was first reported indoors in Thomasville, Ga.: "They were found both indoors and outdoors, including the attic area. Control was achieved with indoor spot applications, treatment of the attic and outside perimeter applications."
SPOTTED MEDITERRANEAN COCKROACH
Ectobius pallidus (Oliver)
The spotted Mediterranean cockroach is from the Mediterranean region and is a household pest in eastern Massachusetts and Michigan, but not in areas in between. Given its distribution in Europe, it has the potential to spread throughout most of the northern United States. It was originally identified as Ectobius livens.
In Europe, it is an outdoor species that enters homes at night. It also has been found on fresh vegetables.
PALEBORDERED FIELD COCKROACH
Pseudomops septentrionalis Hebard
The palebordered field cockroach is a brightly colored insect with a reddish pronotum and yellow markings. It was first collected in Louisiana in 1967 in a men’s clothing store. It is primarily an outdoor species; indoors, it is basically only an incidental pest. It is generally found from Louisiana through Texas up to Oklahoma, Arkansas and in Alabama. This species is particularly common around homes in east central Texas. Near buildings, it is found in heavy ground cover (e.g., ivy), wood piles and landscape mulch.
Ischnoptera bilunata Saussure
The Argentine cockroach was first reported in the United States in Florida. Initially, it was identified as the Nicaraguan cockroach, Ischnoptera bergrothi [Griffini], due to an error in identification. Previously, the Argentine cockroach was known from Argentina, Brazil, Bolivia and Paraguay. In the United States, it is known to occur in Florida and Alabama, but it probably occurs in other Gulf Coast states as well.
Adult Argentine cockroaches are approximately ½ inch to 11/16 inch (15 to 18 mm) in length, brownish dorsally and black ventrally, with two triangular pronotal spots and wings covering the body. Argentine cockroaches have been recorded as being abundant in leaf litter and in open, moist grassy vegetation often near streams or ponds. Both sexes of the Argentine cockroach are active at night and attracted to light. The Argentine cockroach has been mistaken as the Asian cockroach due to its similar behavior and appearance.
FAMILY BLATTIDAE TURKESTAN COCKROACH
Blatta (Shelfordella) lateralis (Walker)
The Turkestan cockroach (see page 72 for an additional story on the Turkestan cockroach) is a semi-arid to arid desert species generally found in temperate regions of the Middle East and the southern region of the old USSR. The biology and life cycle of Turkestan cockroaches is reported to be similar to the oriental cockroach. Like the oriental cockroach, males and females differ widely in appearance. The male Turkestan cockroach is often mistaken for the American cockroach, whereas the female is often misidentified as its close relative, the oriental cockroach.
The Turkestan cockroach was first discovered in 1978 in California, where the species was introduced with household goods belonging to military personnel returning from the Middle East. A second infestation was discovered in 1979 in Texas. The species has since migrated to arid regions across Texas, New Mexico, Arizona and California. The Turkestan cockroach is primarily an outdoor cockroach species and most trapped specimens from indoor glue traps are males. Males are strongly attracted to lights and generally enter buildings after sundown. Occasionally, the wingless females are also found in (indoor) traps. However, the species does not reproduce indoors. The Turkestan cockroach species favors dark, moist environments during the day and can be found in abundance in irrigation boxes and below-ground utility access areas. Based on its native geographic range, the Turkestan cockroach could establish breeding populations throughout much of the southern United States.
Currently, no insecticide resistance is known for the species. Any pest management program that controls the American cockroach or other peridomestic cockroaches should be effective for the Turkestan cockroach. Pest proofing has been successful in preventing pest entry into buildings and current cockroach bait formulations appear to be effective.
FLORIDA WOODS COCKROACH
Eurycotis floridana (Walker)
Eurycotis floridana (Walker) is also frequently called the "woods" roach. Often, it may be found in stacked lumber, firewood, leaf litter, under palmetto leaves, sometimes treeholes and in debris alongside of buildings. It is large, dark brown to almost black, averaging 1.5 to 1.75 inches (3.8 to 4.5 cm) in length. It is an infrequent visitor in homes.
The Florida woods cockroach is the only species native to Florida that occurs in large numbers around structures and is considered an important pest. The range of this species extends along the Gulf Coast through Mississippi and up to the southeast Georgia coast. It is common in communities throughout Florida. Among eight peridomestic cockroach species trapped during a study in Gainesville, Fla., the Florida woods cockroach was the most common (39.3% of the total trapped). Willis et al. (1958) studied the life history of this Florida species in some detail. Oothecae can be produced parthenogenetically, but the hatch rate is low. Each egg case of mated females contains an average of 21 eggs and takes 48 days to develop. Nymphs undergo six to eight molts and development takes 100 and 113 days for males and females, respectively.
When agitated, Florida woods cockroaches of both sexes emit an oily defensive secretion that has a strong odor. A single gland on the underside of the abdomen is the source of the spray that is ejected posteriorly and with some degree of accuracy.
FAMILY BLABERIDAE SURINAM COCKROACH
Pycnoscelus surinamensis (L.)
The Surinam cockroach is a plant-feeding insect that burrows into soil and loose litter for cover. It is capable of destroying various plants and is often carried into homes, shopping malls and restaurants inside potted plants. Although this cockroach is not in the strict sense a household pest, it is a source of annoyance in related structures, such as greenhouses. This species is of moderate size, 3/4 to 1 inch (18 to 25 mm) in length, with wings that extend well beyond the tip of the abdomen. The pronotum is uniformly dark and the wings are a dark olive-green color.
The Surinam cockroach is found outdoors in the lower southeastern United States. Its probable outdoor range is from southern coastal Virginia through the southerly regions of the southeastern United States, including Texas. This species is often found in greenhouses and interior plantscapes and potted plants in parts of the United States where it cannot survive outdoors.
Appropriately labeled residual insecticides or baits have proven effective against Surinam cockroaches in greenhouses, interior plant-scapes and around foundations. Regular yard maintenance and removal of leaf litter, landscape timbers and firewood from around building perimeters will effectively reduce Surinam cockroach harborage.
Leucophaea maderae (Fabricius)
The Madeira cockroach is 1½ to 2 inches (4 to 5 cm) in length. It is easy to distinguish by its large size and the fishnet-like pattern or mottled appearance on their front wings. This cockroach is tropical and frequents the western Mediterranean, various parts of South America, the West Indies, Southern Africa, Bahama Islands and Hawaii.
In the United States, the Madeira cockroach was first reported in New York City where it was thought to have been introduced from Puerto Rico. It is occasionally collected in nearby cities, but it has not become established in other northeastern cities. This cockroach emits a strong odor when disturbed and produces sound by stridulation. It can live under extremely crowded conditions in laboratory containers. Its odor is more repulsive than that exhibited by most cockroaches.
CINEREOUS (LOBSTER) COCKROACH
Nauphoeta cinerea (Olivier)
The cinereous cockroach, so called because of its ashen color, was first discovered in the U.S. in food-handling establishments in Tampa, Fla. This 1 inch (25 mm) long species is sometimes referred to as the lobster cockroach since it has a lobster-like design on the prothorax. The female’s wings are shorter than the body, exposing the abdomen.
In 1970, it was found indoors in San Francisco, Calif. The origin of that infestation is unknown, but it may have been associated with vermicelli flour from the Orient. The species is known to occur in East Africa, Germany, Australia, Hawaii and possibly Florida. It infests grain, fruit and vegetables. In Hawaii, it also has been observed feeding on other cockroaches.
The ootheca has 26 to 40 eggs. The female incubates the ootheca internally. Upon hatching, the nymphs crawl under the female and remain there for about an hour. Adult males produce courtship sounds by stridulation by the pronotum rubbing over the tegmina.
Panchlora nivea (Linnaeus)
The Cuban cockroach is a pale green species that is brought into various ports in bananas from Central America. It has been called it the "green Cuban roach." According to Gurney (1955), P. cubensis Saussure is a synonym for P. nivea (L.).
These cockroaches move about more rapidly than German cockroaches, are capable of flight and are difficult to catch. When placed in alcohol, they quickly lose their distinctive pale green color.
Nymphs are dark brown. This cockroach prefers to live in lawns, in firewood stored outside and in wooded areas that are moist, shaded and have plentiful leaf litter. Currently, the Cuban cockroach is found in many areas of Florida and along the Gulf Coast as far west as Texas. It is attracted to lighted doorways or windows. The standard insecticides used to control domestic cockroaches are also effective against this species.
The author is a senior scientist and program leader at Ecolab’s Pest Elimination Division.