In Massachusetts, two abundant roach species, the German and Brown-banded cockroaches, dwell primarily within human dwellings as opposed to the natural environment. This makes these two species unique among insect pests of homes and buildings. Despite their common name, German cockroaches are native to southeast Asia, but they were introduced into North American by early European colonists hundreds of years ago. Because of this long time span, the German cockroach has become well established in all US states, including Alaska, and it’s the most commonly encountered roach species within homes in the country. While the brown-banded cockroach is also frequently encountered within Massachusetts homes, they are not nearly as abundant in the state as German cockroaches.

The American cockroach is the second most commonly encountered roach species within Massachusetts homes, but this species prefers to dwell in the natural environment. However, German cockroaches are also well adapted to living alongside humans within homes where they are capable of reproducing rapidly. While the German, brown-banded and Oriental cockroach species are between half an inch and slightly more than 1 inch in length, the American cockroach is around 1 ½ inches long, but they often grow to exceed 2 inches in length. Considering their relatively large size, many people cannot help but to wonder how American cockroaches manage to successfully fit through narrow cracks and crevices in order to enter homes.

According to a recent study carried out by researchers at Berkeley, American cockroaches can flatten their bodies to ⅕ their normal running height in order to enter homes through tiny cracks on exterior walls. When American cockroaches run freely, they are around half an inch in height, but they can flatten their bodies down to 1/10 of an inch in order to run through cracks as narrow as two stacked pennies. Additionally, American cockroaches can enter cracks this size in less than 1 second, and they can continue running rapidly while flattened to half their normal size. In an effort to aid search-and-rescue missions, engineers are now building tiny mobile robots that mimic the American cockroaches’ flattening movements.

Have you  ever witnessed a cockroach enter your home through a small entry point?