Through summertime, the acorn grows and hardens. Inside the weevil larva feeds on the seed's interior. In early autumn, the acorn falls off the branch onto the ground below. Soon after, the weevil larva (grub) chews a small hole into the acorn seed and leaves the acorn in early winter, burrowing into the soil. There it can remain hidden from predators while it develops into an adult. The larvae are a protein-packed food source for many other insects, as well as spiders and small animals.
Acorn Weevils can inhibit oak tree expansion if an area is infested. Their larval diet of acorns can result in fewer new oak trees in that area, however, existing trees are not in any danger. Adult Acorn Weevils are hunted by a variety of Weevil Wasps and will eventually become live meals for hatching wasp larvae.