There are few things more annoying than having a bug fly into your ear. But the body is prepared to fend off these insect invasions, says David Hu, a bioengineer at Georgia Tech.

The goop inside our ears may act as a natural insect repellent, Hu’s team reports 28 October in Soft Matter . What we call earwax is not really waxy at all. Instead, the brownish substance absorbs water, a property that might help it regulate moisture in the ear and keep bugs out, the new analysis shows. “[This] familiar biological material may represent a sophisticated physical defense against small arthropods,” says Stanislav Gorb, a functional morphologist at the University of Kiel in Germany, who was not involved with the work.

Researchers have not studied earwax as much as other body fluids, such as snot, spit or even pee. “It’s a big mystery why we even have [it] in our ears,” Hu says. It can frankly seem like a nuisance.…