Introduction:The Smoky Brown cockroach gets its name from its uniformly shining brownish black to dark mahogany color. This species is apparently native outside the United States. It is common in the southern states, from central Texas eastward through North Carolina, but does occur as far north as Illinois, Indiana, and Iowa. It also occurs in southern California.
Adults about 1-1 1/4" (25-32 mm) long. Color uniform and shining, typically brownish black but varies from dark mahogany to black. Both sexes with wings extending beyond their abdomens, good fliers, and attracted to lights.
Nymphal Ist instar black, 2nd instar dark brown; instars 1-3 with mesothorax pale/white but anterior and posterior margins dark, lateral areas of 2nd abdominal segment pale/white, antennae with 4-5 apical segments white but instars 2-3 additionally with about 10-15 segments of the basal 4th pale. Later instars reddish brown but with lateral margins, posterior margins of thoracic segments, and tip of abdomen darker; instars 4-6 with tips of antennae and about 10-15 segments of the basal 4th pale, but late instars with antennae uniform in color. Cerci broadly rounded laterally, length about 4 times width with widest segments about 3 times as wide as long.
Ootheca or egg capsule dark brown to black; usually more than 3/8" (8 mm) long (average 10.5 mm, range 8-14 or average 12-13 mm, no range), with length more than twice width; subdivisional furrows not extending to midwidth; and with 10-14 eggs on each side.
- Similar Groups
- American cockroach (Periplaneta americans), Australian cockroach (P. australasiae), and brown cockroach (P. brunnea) with pale markings.
- Oriental cockroach (Blatta orientalis) with wings reduced, not reaching tip of abdomen.
- Other cockroaches are either smaller or larger, not uniformly brownish black, not fully winged, and/or are not associated with structures.
The female deposits her ootheca within about one day after it is formed. It is usually firmly attached to some surface or object. On the average, the female will produce about 10 (range 4-32) viable oothecae with each containing about 20 eggs (range 4-29).
Developmental time (egg to adult) is greatly influenced by temperature, varying from 160-716 days but averages about 600 days. Adult females live about 218 days (range 127-363) and adult males live about 215 days (range 95-342).
The smokybrown cockroach is common outdoors in the south where it is found in habitats best described as protected, moist, dark, warm, and out of desiccating air flows. These conditions describe the environment of treeholes and other places such as ground cover ivy and vines, loose mulch, woodpiles, and soffits/eaves of attics where there are moisture problems. Smokybrown cockroaches lose moisture through their cuticle more readily than other cockroaches. This is why they favor moist situations and show relatively little movement because of its resulting exposure to desiccating air currents.
They can enter structures by being brought in but they usually enter at night via cracks and crevices through which light penetrates to the outside, light being an attractant to them. Because they are good fliers, they can easily enter via attic openings and are commonly found around eaves and gutters. Inside they can be found anywhere, including attics, but tend to prefer warm and humid areas not exposed to air currents. They feed on any kind of organic matter and do minor feeding on plants. However, once inside they will feed on anything of nutritive value.