The acorn moth larva has three pairs of legs near the head and is generally longer than the legless, fat larvae of acorn weevils. Larvae of the acorn moth feed on acorns and probably on the fungi that often grow in damaged acorns. They usually pupate inside the acorns. The filbertworm, a moth whose larvae closely resemble the acorn moth, is also often found in acoms. Unlike the acorn moth, which usually attacks acorns on the ground, the filbertworm attacks developing acorns on the trees.
Gall wasps are some of the oldest known acorn eaters.
Fossil gall wasps, thousands of years old, have been found in acorns from the famous La Brea Tar Pits of California. Adult females lay their eggs in female flowers of oaks in the spring, which causes galls, abnormal growths of plant tissue, to develop in or on the acorn. Gall wasp larvae live in and feed on the plant tissue inside the galls. It is a blood-red globe about an inch in diameter that is attached to the acorn cup. Many of these external galls drop off the acorns in the autumn.