Missouri's Araneus spiders, called angulate and roundshouldered orbweavers, can be hard to identify to species. Most have camouflage patterns, and they all make characteristic, delicate, wheel-shaped webs to catch prey.
The brown recluse is one spider to avoid. It is venomous, though a bite is almost never fatal. Brown recluses are most commonly encountered in houses, where they occupy little-used drawers, closets, and other small hiding spaces.
The aquatic larvae of caddisflies are famous for building portable, protective cases out of local materials, including grains of sand, bits of leaves and twigs, and other debris. The adults are mothlike.