1. Any of various small, principally nocturnal mammals of the order Insectivora, characteristically feeding chiefly on insects and including the shrews, moles, and hedgehogs.
2. An organism that feeds mainly on insects.

Although individually small, insects exist in enormous numbers and make up a very large part of the animal biomass in almost all non-marine environments.

In Queensland, Australia, pastures; for example, it is normal to have a greater total weight of Scarabaeidae larvae under the surface of the ground than of the beef cattle grazing above it.

A great many creatures depend on insects as their primary diet, and many that do not (and are thus not technically insectivores) nevertheless use insects as a protein supplement, particularly when they are breeding.