Twig Girdling Beetles

The twig girdler (Oncideres cingulata) is a longhorn beetle. Each fall, usually September through November, these beetles neatly girdle tree branches about the diameter of a pencil. The branches will fall to the ground and by the time you find them, the beetle that girdled the branch has left. Because of this, the adult beetle is seldom seen. 

The adult beetle is about 1/2 to 3/4 inch long, has antennae about as long as its body, and is grayish brown with a broad ash gray band across the middle of its back. Adult beetles emerge in the late summer and fall and locate a host tree.  

In the host tree, they chew around the branch forming a V-shaped notch. They usually don’t completely sever the branch, but leave a small section connected in the center. The partially severed branch usually breaks from the tree and either falls to the ground, lodges in the tree crown, or hangs loosely attached where it was girdled.  

Close examination of the severed branches reveals tiny scratches where the beetle has chewed the bark. The female beetle lays about ten eggs on each severed branch and may deposit a total of 200 eggs. The eggs hatch in about three weeks and the larvae feed in the cut branch. In late summer, the larvae pupate and about two weeks later emerge as adults. There is one generation per year and adults generally live six to 10 weeks.  

Impacts 

Damage from twig girdlers is more common some years than others. The preferred hosts include pecan, persimmon, hickory, walnut, red oak, hackberry, elm, mesquite, among others. 

They seldom do any serious harm to trees and are mostly a nuisance. On some occasions though, they have been known to cause significant damage in pecan orchards and nurseries.  

Control

Insecticide applications are rarely justified or practical in landscapes. Insecticides may be necessary to prevent damage from heavy infestations in some hardwood tree nurseries.  

Instead, collect and destroy clipped branches. The branches that fall from a twig girdler’s work should be collected and destroyed because the eggs are living inside the branch.  

The following photographs show typical signs of twig girdler activity. The first picture clearly depicts the precise cuts the adult beetles have made on pencil-sized twigs. Notice that a thin section in the middle of the twig was not cut but the twig has broken off.