Choose the odd one out: Ant, Butterfly, Spider, Beetle.

The ant, the butterfly and the beetle are insects: six legs and a body in three parts. A spider carries eight legs and a body in two parts, which places it among the arachnids. It is tempting because it is small, many-legged and turns up in the same corners of a garden, but the shared property here is being an insect, not merely being a crawling creature.