Insect: Small animals with three pairs of jointed legs and one pair of antennae, at least in the adult phase. Mole crickets, tachinid flies, and crabronid wasps all have this arrangment in the adult phase, and mole cricket nymphs also have it. However, some insect larvae (grubs) are legless. Spiders and ticks have four pairs of jointed legs, centipedes and millipedes have many more pairs, and these are not insects.