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What Are the Different Sizes of Roaches?

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There are approximately 3,000 species of cockroaches, with about 50 species making their homes in the United States. Roaches vary from less than a half-inch long to about 3 inches. Smaller varieties have adapted to share human habitations, but larger species are more common outdoors.

Small Cockroaches

The German brown cockroach (Blattella germanica) lives in homes throughout the United States and grows up to 5/8 inch long. These roaches' flattened bodies can pass through tiny crevices, where they often nest. Brown-banded roaches (Supella longipalpa) grow to similar size, flourishing in office buildings, dorms and libraries where they can feed on paper products, glues and electronic wiring. The Kenyan roach (Blaberidae sp.) rarely exceeds 1/2 inch and is an ideal feeder roach for small insectivores.


Wood roaches (Parcoblatta pennsylvanica, Eurycotis floridana) are native throughout North America and average an inch or more long. These roaches are often seen around porch lights on summer evening, and they sometimes inadvertently find their way into the home. They depend on wood and leaf litter for breeding and food and need moist environments, and they won't reproduce inside your home. Smoky brown roaches (P. fuliginosa) are native to the Southeast and reach 1.5 inches.


Moist summer nights stimulate the country's largest roach to venture from underground burrows to feed and mate. The American cockroach (Periplaneta americana) thrives in sewers, boiler rooms, restaurant kitchens and other humid areas where food is plentiful. This roach ranges from 1.5 to 3 inches long. Madagascar hissing cockroaches (Gromphadorhina portentosa) are popular as pets and can reach 3 inches. They are easily kept in aquariums and can live up to 5 years in captivity.


The largest cockroaches in the world hail grow to more than 3 inches long and are native to the Southern Hemisphere. They make popular pets in the United States. The Central American giant cockroach (Blaberus giganteus) is the longest known species, while the Australian rhinoceros cockroach (Macropanesthia rhinoceros) is the heaviest -- more than an ounce when it reaches its adult length of 3 or more inches. The rhino's life span can exceed 10 years.