Vermin

Animal pests and parasites that either attack human beings directly or contribute to the spread of infectious diseases as pathogenic agents, or else spoil or damage food supplies and implements in trenches and sleeping quarters.

Bedbugs, lice, fleas, mice, rats, cockroaches, mealworms, and larder beetles in particular were regarded as vermin in this sense. In the European war theaters, bedbugs were not carriers of diseases, but still proved a nuisance as blood-feeding insects whose bites caused unpleasant wheals and itching…