What classifies an insect as a beetle? All beetles share a number of anatomical characteristics which differentiate them from other insects.  These are: 1) armored forewings or elytra which typically meet in a straight line and provide a protective cover over the underlying hind wings, 2) membranous hind wings which are generally longer then and folded under the elytra, 3) the antennae are variable in morphology and typically have 11 segments, 4) mouth parts are designed for chewing with mandibles, 5) the number of tarsi segments ranges from 3 to 5, 6) typically 5 abdominal segments which can be seen clearly on the ventral side and 7) beetle metamorphosis is complete with the adults differing in appearance from the larva.