For Release October 30, 2001

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

Okay, if you have little black gnat like bugs all over the outside of your house and screens, raise your hands. Uh-huh, just as I expected... a lot of you. Now, how many of you have a hackberry tree in your yard or your neighbor’s yard? Looks like about the same number of hands. Well, there is a correlation. Oh, you can put your hands down now.

The little black bugs are not a fly or a gnat. They are not dangerous, and contrary to what you may have felt or heard, they do not bite. The insect is officially known as the hackberry nipple gall maker or the hackberry psyllid. These insects are in the same insect order (homoptera) as cicadas (locusts), leafhoppers and aphids. Hackberry psyllids are responsible for the bumps on the hackberry leaves during the summer.

The hackberry psyllid starts life as an egg laid on young developing hackberry leaves in the spring. The young psyllid starts feeding on the leaf and the leaf very quickly develops a little pocket that the small insect crawls inside of. The pocket then seals over and the immature psyllid spends the rest of the summer sucking on tree sap safely tucked away inside the little green gall. The feeding damage is minimal and appears to do very little harm to the tree.

In late summer the immature psyllid pupates (forms a cocoon of sorts to change from an immature to an adult). In the early to mid fall, the adult psyllid emerges. This is what we are seeing right now. These critters will swarm in the hundreds and thousands and land on almost anything. They have one thing in mind right now. Finding a location to hibernate through the winter.

If they do come inside your house, they will not cause any damage, other than being a nuisance. They have a piercing sucking mouth. They won’t chew holes in clothing or eat food. They only feed on hackberry trees so they won’t be a problem on house plants. They have stout little legs. If they land on you it may feel a little prickly, hence the sensation of being bitten. They don’t bite and should not be feared.

Unfortunately, there isn’t a lot we can do to reduce their numbers. Many times they’ve already emerged from the leaf galls before the leaves fall off the trees. Raking the leaves probably won’t help reduce their numbers. They are nearly impossible to control in the spring. There is such a short period that they are vulnerable to sprays before being enveloped in the gall that spraying isn’t practical then either. There are some natural predators that can help reduce the numbers. Like all insects, there are cycles in their populations. Right now we just happen to be at a high in their population cycle.

If you have large numbers on the side of the house you could spray them with a general yard or garden insecticide. But there’ll probably be just as many tomorrow and they’ll be unaffected by the residual sprays. You are probably better off to just hose them off with a garden hose. Spraying under the hackberry trees and around the leaves won’t do any good either, as most of them have left that area already. They’re all on the side of your house.

As the weather become cooler their activity will decrease and hibernation will set in. But with every warm spell, like this week, for the next month, we can expect to continue seeing problems with these rascals.

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