Control not needed for hackberry psyllid
By Linda Langelo
Golden Plains Extension Horticulture Program Associate
Hackberry nipple gall maker is a gall that is formed on the undersides of leaves of the hackberry tree by the hackberry nipple gall psyllid. What are psyllids? They are small insects that are about a tenth of an inch long when full grown. They look like miniature versions of cicadas. Unlike cicadas, they have an ability to jump. They are quite host specific or in other words, specific to a family or a genus of plants.
In the case of hackberries, these psyllids produce a prominent wary leaf gall on the undersides of the hackberry leaves. These galls resemble a little green pea. When the buds of the hackberry begin to expand, the adults emerge and deposit eggs on the undersurface of the leaf. As the eggs hatch, the nymphs feed and this swelling or gall begins to form. At the end of the summer when the nymphs reach their adult stage, they emerge. There is only one generation per season.
This process leaves the tree looking ugly. However, these psyllids have a purposeful life cycle according to Whitney Cranshaw, Colorado State University Entomologist. Hackberry psyllids are prey for chickadees, creepers, nuthatches, and many other species. In the spring, migratory birds such as warblers, ruby-crowned kinglets, pine siskins, American goldfinches and chipping sparrows rely on these psyllids. The nipple galls are eaten by fox squirrels.
The berries produced on the hackberry provide a food source for other birds. These birds are ring-necked pheasant, robins, mockingbirds, quail, wild turkey, cedar waxwings, sharp-tailed grouse, yellow-bellied sapsuckers and other birds.
These psyllids do not need to be controlled for the health of the tree. Mother Nature has provided a balance. A food source for the birds while not harming the tree and then, only in rare cases. For more information visit www.ext.colostate.edu.