| Common Name | Scientific Name |
|---|---|
| Hackberry Nipplegall Maker | Pachypsylla celtidismamma (Riley) |
| Hackberry Blistergall Maker | Pachypsylla celtidisvesicula (Riley) |
During the autumn months, homeowners with hackberry trees often become annoyed by large populations of adult jumping plant lice or psyllids. These tiny, dusky, gnat-like insects often cluster on window and door screens (many pass through ordinary house fly screens into the home), settle onto sides of houses, automobiles and hanging laundry and accumulate into freshly applied paints. Although they do not bite, sting, carry disease or feed on human possessions, they are a nuisance by their presence, appearing to be attracted to bright colors and night-lights. Usually adult infestations are short-lived.
Adults are about 1/8 to 3/16 inch long, dusky-black and white mottled insects (usually with dark spots on the wings). They are wedge-shaped, resembling tiny cicadas and winged aphids. Both sexes have wings, the hind legs fitted for jumping (jumping plant lice), antennae slender and prominent (9 to 10 segments), four membranous wings (front wings larger), and a beak that appears to arise between the front legs. Eggs are ovoid (egg-shaped), shiny-white and deposited on new leaves of hackberry trees. Nymphs live inside leaf galls throughout the summer months.
Adults overwinter (hibernate) in the bark crevices of hackberry, sycamore, oak and other trees, in buildings or houses at window and door ledges, in vegetation and other protected locations. In the spring, during the warm days of April (temperature in the 50 degrees F range), adults become active, flying to hackberry trees where mating and egg laying occurs, continuing toward the end of May. Eggs are deposited within new leaf tissue, forming a "gall" on the underside of hackberry leaves. There is an interval of 10 to 12 days between egg hatching and gall formation. It is the nymph feeding activity that stimulates abnormal leaf growth, producing the gall that encloses and protects the nymph during its period of growth. The hackberry nipplegall maker causes mammiform (nipple) galls whereas the hackberry blistergall maker causes blister-like galls on the underside of hackberry leaves smaller and much more numerous than the nipple galls. Although hackberry leaves are disfigured by numerous galls on the undersides, the growth and vigor of these trees are not retarded to any noticeable extent. One nymph, or immature, is present in each gall. Nymphs mature and then exit the gall once leaves have fallen. They cut a slit in the gall to permit emergence. Thirty minutes later, nymphs molt to adults. Several thousand adults may emerge from a single hackberry tree in late-September, reaching their peak in October. Periods of warm, dry, autumn days favor ideal development and survival of psyllids.
Infestations are usually short-lived (few weeks) depending on the temperature. They will remain active as long as the temperature is above 50 degrees F. When the temperature reaches down into the 40 degrees F range, they will rapidly dissipate and go into hibernation for the winter.
Some neighborhoods remain free of infestations since adults do not migrate far from the hackberry trees. Usually all leaves of the hackberry tree have galls. Consequently, removal of hackberry trees would eliminate problems with adult psyllids. However, if trees are needed for ornamental and landscape beauty, be sure to carefully caulk all crack and crevice entry sites around doors, windows and foundations. These adults can pass through ordinary house fly screens having 12 mesh to the inch. It may be practical to use mosquito screens having 18 mesh to the inch. Installing storm windows and doors before adult emergence is helpful. Use good night-light discipline, especially over doors and windows when adults are present. Use special yellow lights not attractive to insects. Mercury-vapor lamps at entrances should be replaced with sodium-vapor lamps.
Indoors, household pressurized aerosol sprays of pyrethrins, sprayed where adults are present, will give good kill. The use of a strong suction vacuum cleaner with proper attachments will quickly collect many adults that get into the house. Outdoors, residual sprays of chlorpyrifos (Dursban) applied to window and door frames, screens and house foundations will reduce entry into the home.
Control is best achieved in the spring by spraying the hackberry trees before protective galls are formed around the nymphs (immatures). Egg laying occurs over several weeks when new leaves unfold from the bud. Leaf growth and adult egg laying will depend on spring temperatures. Sprays are usually applied in late-May or early to mid-June. Repeat applications are usually needed. Even though the number of galls can be reduced by properly timed sprays, the operation may be unpractical except on small hackberry trees. Labelled pesticides include carbaryl (Sevin), chlorpyriphos (Dursban, Pageant), azadiractin (Bioneem), cyfluthrin (Decathion, Tempo), acephate (Isotox, Orthene), Dimethoate, fenetrothion (Pestroy), Pyrethrin, Rotenone, petroleum oils and soaps. If necessary, commercial applicators can apply soil injections of systemic insecticides such as Dimethoate. Before using any insecticide, always read the label, and follow directions and safety precautions.
This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author, The Ohio State University and Ohio State University Extension assume no liability resulting from the use of these recommendations.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868