Cockroaches Have a Forceful Bite That They Don’t Use

By Chris Williams on December 14, 2015.

Here’s a new fun fact about cockroaches. They can bite with a force 50 times their body weight. Who ever figured that out?

A European research team headed by Tom Weihmann set out to study insects’ mandibles, otherwise known as jaws. They strapped ten American cockroaches upside down onto a “table” with their heads immobilized and glued in place with dental cement. No wonder they bit when they were then jabbed with a probe containing a sensor device. Two of the cockroaches were actually removed from the study because they bit down so hard that they broke two of their “teeth.”

May the Force Be With You

After recording data on 300 bites, the researchers were able to calculate the average amount of pressure on the cockroaches’ mandibles. They found that cockroaches can bite with a force 50 times their own body weight. Or, a cockroach’s bite is about 5 times more powerful than a human’s bite, if you take into consideration the body weight of each test subject. The roaches also had two different types of bites, one that used fast-moving muscles to produce short, weak bites, and the other resulting in long, hard bites requiring more muscle force to chew through tougher materials.

Why Cockroaches Don’t Bite People

But “wait a minute,” you say, “we thought that cockroaches didn’t bite. In fact, your blog says so” (see Many Insects Can Bite People…But Don’t). Just because cockroaches can bite, that doesn’t mean people are a target. Cockroaches rarely bite people because (1) there’s no reason to, people aren’t seen as food; (2) when threatened, cockroaches rely instead on their running speed and ability to hide in cracks, biting is not part of their defense mechanism; and (3) cockroaches are rarely handled by people, for obvious reasons.

Most insects with a noticeable bite that can break skin are those that are predators on other insects and so have more developed jaws and the inclination to use them. A bite from a cockroach, if you feel it at all, would feel more like a light nip. Then why do cockroaches need such forceful jaws if they don’t seem to use them? Good question, that we can’t really answer. The larger American cockroach has a varied diet and does occasionally chew on wood and leather, requiring heavy-duty jaw muscles. But maybe cockroaches are just pre-adapted to take over the world and are waiting for their moment!

[Research article: Weihmann, Tom et al. “Fast and Powerful: Biomechanics and Bite Forces of the Mandibles in the American Cockroach Periplaneta americana.” PLOS One, Nov. 11, 2015.]



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