Cockroaches can bite up to five times harder than humans.

Une étude montre à quel point ces insectes sont pleins de ressources insoupçonnées.

We can say what we want about cockroaches, but when it comes to biting life, food, detritus and corpses with full teeth (or rather with full mouth parts as we say in invertebrates), few species compete with them. This is the result of a study, mentioned here by Gizmodo, published in the journal PLOS ONE and carried out by researchers from the University of Cambridge. The investigation, nourished by 300 cases of cockroaches, thus establishes that these insects can bite with a force exceeding fifty times their own weight and five times stronger than a human being.

Of course, one might wonder about the usefulness of such an investigation, but its director Tom Weihmann reminds us that cockroaches represent a large part of the biomass on earth, are essential to multiple decomposition processes and as such, primordial for the ecological balance.

The trick that kills

The conclusion of the study is strong, its motivations deep, but carrying it out was a different matter. Each time, the scientists had to stun the bug by cooling it down for a while and then press its back against an aluminum plate. The invertebrate’s head was secured under a notch to keep it still and allow it to bite into whatever was presented. Because two precautions are better than one, the cockroach’s skull was also stuck in dental cement.

The strength of the cockroach bite is variable. It is only fully expressed when the material deserves it: to nibble wood, for example.

However, the body, let alone the head, of the insect is much too small to house the enormous muscles capable of providing this energy. But the cockroach is clever and does things differently: it makes the fibers of its muscles play, contracts them, alternately quickly and slowly, so as to increase its strength tenfold. Tom Weihmann explains that these movements allow the cockroach to “give more energy to its mandibles and increase their power to 0.5 Newton” during a sustained effort to chew. Unfortunately, the cockroaches in the experiment were killed in the tests.