INTRODUCTION
The Brown cockroach is often mistaken for the American cockroach which it closely
resembles in appearance and habits. It is primarily tropical in distribution and probably
of tropical African origin. Although found mainly in the southern United States westward
through Texas, it occurs as far north as Philadelphia, Pennsylvania, and Columbus, Ohio.
It has been introduced into California several times but apparently is not established.
RECOGNITION
Adults about 1 1/4 - 1 1/2" (33-38 mm) long. Color dark reddish brown except
for an irregular and sometimes faint yellowish brown to brown submarginal bandlareas near
edge of pronotal shield. Last segment of carcus short and triangular, length less than
twice width. Wings fully developed with male's barely extending beyond tip of abdomen;
tend to glide rather than fly.
Nymphal early instars brown to dark brown; lst instar with abdominal
lateral margins much darker except basal 2 segments with faint lateral spots; instars 1-4
with mesothorax pale/white but anterior and posterior margins dark; instars 1-5 with 2nd
abdominal segment having pale lateral areas; antennas with basal 4th pale in instars 1-4
and with 4-5 apical segments white in instars 1-2 or tips pale in instars 3-4. Later
instars reddish brown with lateral and posterior margins of segments darker and paleness
on mesothorax, 2nd abdominal segment, and antennae fading out. Cerci broadly rounded
laterally, length about 4 times width with widest segments about 3 times as wide as long.
Ootheca or egg capsule brownish when deposited, then turns black; about 1/2" long
(average 11.7 mm, range 7-13.5 or average 13.5 mm, range 12-16), with length more than
twice width; subdivisional furrows extend entire width; keel not extending downward to
beyond 1/4 of width of end with terminal point; and with 12-14 eggs on each side.
SIMILAR GROUPS
(Adults only)
- American cockroach (Periplaneta americans) with last segment of
cercus at least 2 times longer than wide.
- Australian cockroach (P. australasiae) has front wings with outside
margin at bass pale yellow.
- Smokybrown cockroach (P. fuliginosa) uniformly brownish black.
- Other cockroaches are either smaller or larger, lack characteristic
pale markings or characteristic terminal cercus segment, and/or are not associated with
structures.
BIOLOGY
The female deposits her ootheca within a day after it is formed. It is securely
glued with a mouth secretion to a suitable surface in the open near the ceiling, usually
on plaster or concrete. The female often covers her ootheca with plaster which she has
removed from the surrounding area, thus making the ootheca blend in with the plaster
background. The female will produce up to 32 oothecae with each containing an average of
24 (range 21-28) eggs.
Developmental time (egg to adult) is strongly influenced by
temperature, but at room temperature it averages about 224-340 days. This cockroach can
reproduce parthenogenetically (without fertilization by a male) but the hatch rate is 9%
and only about 1/3 of these reach maturity, all being females. Adults live about 244 days
(range 64-392) but some have been kept alive for more than 20 months.
HABITS
The brown cockroach prefers hot and humid areas and is usually found in the same
areas/sites one would expect to find American cockroaches. Such places include
food-storage areas, basements, crawl spaces, grocery stores, and sewers. In the South,
they survive quite well outdoors and are found in leaf litter, ground cover, in
association with trees, especially palm trees, and around dumps.
They enter structures by being brought in, through cracks or holes
in exterior walls, and through sewers. The brown cockroach normally feeds on plant
materials.
