With this insect problem you would think tiny beavers were in your trees! Small branches accumulating on the ground and the presence of clean-cut twigs, and in some cases dangling (flagged) branch tips within a tree, indicate the presence of beetle pests referred to as twig girdlers and twig pruners. Both of these long-horned beetle species attack numerous types of shade, nut and fruit trees. Heavily damaged trees appear ragged and unattractive, and young trees can become deformed by repeated attacks.
Twig girdler (Oncideres cingulata)
Common hosts of the twig girdler include dogweed, persimmon, pecan, elm, hickory, oak, honeylocust, hackberry, poplar, linden, redbud, basswood, and various fruit trees.
The adult beetle is about three-fourths of an inch long, stout, grayish-brown with a lighter colored band across its elytra (wing covers) and has antennae as long as its body.
Adult beetles typically begin to emerge in mid-August and continue through early October. During this time, the adult female chews a V-shaped groove around a small twig, girdling it. She then deposits an egg beneath the bark in the twig section beyond the cut (severed portion). This is because the larva is unable to develop in healthy sapwood. The cut made by the adult female is deep enough around the twig so that the girdled portion dies quickly and usually falls to the ground, either because of wind or its own weight.
During the oviposition period, large numbers of girdled twigs often accumulate beneath the tree each day. After hatching from the egg, the developing larva bores into the dead twig to feed. The small larva will overwinter in the fallen twig. During the following spring, the larva resumes feeding, consuming most of the wood.
As the larva grows it bores further down into the twig and fills the tunnel with wood shavings and waste. Pupation occurs in a cavity within the twig. Adults emerge in late summer and early fall. Twig girdlers produce one generation a year.
Homeowners should collect and destroy infested twigs and branches they find on the ground, beginning in September or no later than May. If practical, prune infested twigs still in the tree.