Foresters are using parasitoids to reduce the spread of the emerald ash borer beetle, following the lead of many states to ...

Learn about the wasps that have a gruesome but fascinating way of surviving.

Q • My oak trees have more large galls than I’ve ever seen on them, and I’m worried about their health. What can I do about ...

Galls form when certain wasps, including species like Kokkocynips decidua and Kokkocynips rileyi, lay their eggs in oak tissues. These growths become shelters where wasp larvae develop.

The galls are filled with fibers and small seed-like capsules, which is why they are also known as oak seed galls. Each of these “seeds” contains a single wasp larva.

Hugo’s father, Andrew Deans, a professor of entomology at Penn State, identified the objects as oak galls – abnormal plant ...

Gall wasps are a small breed of wasps that lay their eggs in Oak and Pecan trees. Their eggs grow into the tree, leaving a hard capsule around it, which the larvae inside will eventually eat.

A more commonly seen gall formed by a different type of wasp is the brown, papery oak apple gall. The size of a ping pong ball, it’s found on oak leaves.

The two-horned oak gall wasp is just one of dozens of species of gall wasps that incubate their eggs in oak leaves.

The wool sower gall (Callirhytis seminator) and oak wart gall wasp (Callirhytis quercusfutilis) only cause cosmetic damage to leaves.

Hedgehog galls appear on oak leaves as clumps of bristly pink fur, while wood sower galls look like white or creamy cotton balls. The fluff is actually a group of wasp-induced galls.

Oak galls are caused by gall wasps, a small cynipid wasp. The female wasp lays her eggs on the tree. This irritation causes the abnormal plant growth we call a gall. The many species of gall wasps ...