Borers are beetle or moth larvae that develop under the bark of trees, damaging the wood and eventually killing the tree. Unhealthy trees are more susceptible to borers, so the best defense is to keep your oak tree (Quercus spp.) watered, fed and properly pruned.

What is attacking my oak trees?

Borers and some leaf-eating insects, such as worms and caterpillars, can seriously damage oak trees (Quercus spp.). … Generally, healthy oak trees can withstand leaf- and wood-eating insects, but weak or young oaks may die after severe insect damage.

What insect eats oak leaves?

The California oakworm (Phryganidia californica, family Dioptidae) is one of many species of caterpillars that feeds on oaks. It is the most important oak-feeding caterpillar throughout its range, which extends along the coast and through the coastal mountains of California.