Periplaneta americana adults are about 1 3/8 to 2 1/8 inches (34-53 mm) long. Their color is a reddish brown except for a submarginal pale brown to yellowish band around the edge of their pronotal shield (Pronotal shield - an expanded version of the top surface plate of the front segment of the thorax). Both sexes are fully winged. The wings of males extend beyond the tip of the abdomen, while females' do not. They are poor to moderately good fliers.

Early instars of Periplaneta americana nymphs are uniformly grayish brown dorsally, paler ventrally, and shiny. The cerci (cercus [pl. cerci]- One of a pair of dorsal appendages at the posterior end of the abdomen) are slender, and distinctly tapered from the base with length about 5 times the width. Later instars are reddish brown with lateral and posterior margins of the thorax and lateral areas (sides) of abdominal segments somewhat darker. The cerci are about the same as in the early instars. The widest segments are 2.5 times as wide as long. The antennae are uniformly brown.

The cockroach's walking pattern can be described as follows:

"The cyclic movement of a walking leg consists of two parts, the power stroke (also stance phase or support phase) and the return stroke (also swing phase or recovery phase). During the power stroke, the leg is on the ground where it can support and propel the body. In a forward-walking animal, this corresponds to a retraction movement of the leg. During the return stroke, the leg is lifted off the ground and swung to the starting position for the next power stroke."

(Cruse 1990; Cochran 1980; Smith & Whitman 1992; Bio-Serv 1998)

The adult Oriental Cockroach is a shiny black or dark-brown color. The younger members are darker and not shiny like the adults. The male of Blatta orientalis is smaller than the female. Males are about 2.6 centimeters in length, while females tend to be from 2.6 to 3.25 centimeters in length. The average male weighs approximately .45 grams while the female weighs .95 grams. The male is also more slender than the female, whose abdomen is broad in comparison to his. Another difference between the male and female of the species is that while the male has wings that almost reach the abbomen, the female only has pads as her wings. Although both have wings or pads, neither can fly. The nymphs have a similar shape to the adults, but unlike the adults, are wingless (Cornwell 1976; Lyon 2000).