Herself's Houston Garden

Conservation through cultivation

Twig girdlers

My only experience with twig girdlers so far has been on my river birch. There are always twigs under the tree and I had thought that river birches just shed old branches naturally. But this is not so, it is twig girdlers who are stripping the twigs from the tree.

Twig girdlers are very common across Texas and we have several species of them. All have antennae that is twice as long as their bodies on the males, and same size as bodies on females. They range from a half inch to just under an inch in size. Colors vary by species, but they are shades of brown and grey and speckled with pink, yellow or orange spots.

After mating the female selects a tree branch. She then cuts into the bark until a clean circle is made around the twig. Then the female girdler makes notches around the circle and lays eggs in the notches. About a week later larvae hatch. The larvae then feed on the dead wood of the branch borrowing beneath the bark. A year later they emerge fully grown, usually in late summer into early autumn. Later branches fall from tree as the weather and time further weaken them.

Most deciduous trees can be attacked by tree girdlers.

The most effective control is to immediately remove branches that have fallen and likely contain young girdlers. Insecticides are rarely effective.