The unusual weather this year has set up conditions for a very obscure moth to come out of obscurity and defoliate many of the hackberries in southern Denton County.
The moth larvae is a small green caterpillar about 1/2 inch long at maturity. The caterpillar is called a “skeletonizer” because it eats the flesh out of the leaves and leaves the veins, making the leaf look like a skeleton.
If you are seeing this on your hackberry trees, they aren’t dying. They look like they are dying, but they are not. A healthy tree can withstand a complete defoliation. They will come back in full leaf next spring. We may see some new leaves form this year if we get some rain and cooler weather.
Treatment is not really recommended. By the time you see the damage, the caterpillars are done feeding and any treatment just kills the caterpillar’s predators and does nothing for your tree.
Here are a couple of links to some information on the caterpillar: