Identification
Adults
P. americana (American Cockroach) is the most common Periplaneta in the US:
P. australasiae (Australian Cockroach) has a more contrasting pronotal pattern and white bands on the outsides of the wings:
P. fuliginosa (Smoky Brown Cockroach) has pronotum uniformly dark (no pattern):
P. brunnea (Brown Cockroach) may be difficult to differentiate from P. americana but the cerci are more stout
Early Instar Nymphs
P. americana: usually solid brown with minimal variation in the hue over the body:
[the image that was here,
207381, was later reidentified as
P. fuliginosa.]
P. fuliginosa: black, with white antennal base and tips; a band on the thorax; and two lateral marks on abdomen:
P. australasiae and P. brunnea nymphs have similar yet less contrasting white markings on antennae, throax and abdomen
Late Instar Nymphs may be difficult to separate, with the exception of P. australasiae which have developed the more contrasting colors seen in the adults:
late-instar P. brunnea show variable markings:
late-instar P. americana vary from light brown with little markings to light brown with darker markings
Remarks
The Japanese cockroach P. japonica was discovered in Manhattan, NY in 2013. It is cold tolerant and has the potential to spread in the wild.
Adult males have about 250,000 sensilla on each antenna
(1)