Cockroaches, Order Blattodea

The order Blattodea includes the cockroaches, insects unfairly reviled the world over. Though some are pests, most cockroach species fill important ecological roles as scavengers that clean up organic waste. The order name comes from blatta, which is Latin for cockroach.

Description

Cockroaches are ancient insects. They've remained almost unchanged for over 200 million years. Roaches run fast on legs adapted for speed, and with 5-segmented tarsi. Cockroaches can also accelerate and turn quickly. Most are nocturnal and spend their days resting deep within tight-fitting cracks or crevices.

Roaches have flat, oval bodies, and with a few exceptions are winged. When viewed dorsally, their heads are concealed behind a large pronotum. They have long, slender antennae, and segmented cerci. Cockroaches use chewing mouthparts to scavenge on organic materials.

Members of the order Blattodea undergo incomplete or simple metamorphosis, with three stages of development: egg, nymph, and adult. Females encase their eggs in a capsule called an ootheca. Depending on the species, she may place the ootheca in a crevice or other protected place, or carry it with her. Some female cockroaches carry the ootheca internally.

Habitat and Distribution

Most of the 4,000 species of cockroaches inhabit moist, tropical environments. As a group, however, cockroaches have a wide distribution, from desert to arctic environments.

Major Families in the Order

• Blattidae: Oriental and American cockroaches
• Blattellidae: German and wood cockroaches
• Polyphagidae: desert cockroaches
• Blaberidae: giant cockroaches

Cockroaches of Interest

• The Madeira cockroach (Rhyparobia maderae) can stridulate, an unusual skill for a roach. It also gives off an offensive odor when threatened.
• The tiny Attaphila fungicola cockroach inhabits an ecological niche – the nests of leaf-cutting ants.
• Madagascar hissing cockroaches (Grophadorhina portentosa) force air through their spiracles to produce a hissing sound. They're a popular pet insect.
• The giant cave cockroach, Blaberus giganteus, feeds on bat guano among other things.