The Purdue Plant and Pest Diagnostic Laboratory

What's Hot at the P&PDL
November 5, 2012

Hackberry Nipple Gall-making Psyllid

Timothy J Gibb, Insect Diagnostician, Department of Entomology, Purdue University

This is one of my favorite insects. Not because it is big or colorful or flashy or even very interesting really, but what I like about this insect is its name. I just love saying it. I would have named one of my children after it, but their Mother failed to appreciate the poetry in it.

Hackberry Nipple Gall-making Psyllid. The name alone suggests that these are the cause the small discolored nodes that are so common on the undersides of hackberry leaves. Psyllids are a group of small insects called jumping plant lice, and the name fits. They are tiny, plentiful at times and they do jump when disturbed.

In the fall time, adult Hackberry psyllids emerge from their galls and fly, sometimes congregating on windows and screens. They are often described as tiny black jumping insects and are quite small - small enough to actually pass through the mesh of many window screens. That is why homeowners report them as being a nuisance in the home.

Under a microscope Hackberry psyllids resemble a miniature cicada – large eyes and with wings held roof-like over the back. They pass the winter as adults and lay eggs again in the spring-time on the emerging leaves of hackberry trees. When the eggs hatch, the tiny nymphs act like other gall-making insects by causing the leaves to form the distinctively shaped gall that they are named after. The tiny nymphs live and grow inside this protective gall and as summer progresses, the leaves can sometimes be covered with them.

These are not a serious pest of hackberry trees because the galls, although very conspicuous, do very little damage to the leaf. Hackberry psyllids are mostly considered to be a nuisance pest when they get into homes.

Chemical treatments are seldom warranted. To prevent them from entering the home simply close the windows during the short period of time when they are active. Alternatively, you may go to the hardware store and ask for window screens with a small enough mesh to exclude Hackberry nipple-gall making psylids. I’m sure they will know just what you are talking about. Even if they don’t you will sounds smarter just for saying it.

Click image to enlarge

Hackberry nipple gall-making psyllid on leaf

Hackberry nipple gall-making psyllid on gall

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service