Why Are My Oak Trees Losing Limbs?

Identifcation

• Oak trees are likely to get infested with twig girdlers, a species of long horned beetles. Adult twig girdlers are ¾-inch-long, gray-brown beetles with antennae and light bands across the wings. Young oak trees can be severely deformed by an infestation.

Damage

• Adult female girdlers emerge between August and October and chew grooves around twigs and branches to deposit eggs. The damaged area starts to die and eventually severs the entire limb or twig from the tree. The larvae feed on the fallen twigs and overwinter in them, emerging as adults the next summer. The pests produce one generation every year.

Management

• Remove and destroy all fallen twigs and branches under the tree. It is also best to prune out all damaged limbs still attached to tree to minimize population the next year. Chemical control options include the use of carbaryl. Apply two or three times every week in cases of severe infestation.