mites1

The feces of dust mites isn’t just a byproduct of digestion, but a potent, biologically active substance vital to their procreation. There isn’t much to eat in the mites’ austere, dusty habitat, says Pavel Klimov at Michigan University, so they developed a very strong digestive enzyme—a protein called cysteine protease, which helps them break down tough material that is available to them, like dead cells.