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Problem: Hackberry Nipple Gall Psyllid - Pachypsylla celtidismamma
Hosts: Hackberry is the only known host of this pest.
Description: These galls are caused by tiny insects known as psyllids (sill-lids). Infestations of hackberry are extremely common, but do not seriously affect the vitality of the tree, although heavily infested leaves may drop prematurely.
Nipple galls, as the name implies, are medium sized (1/4 inch tall) nipple-shaped galls on the undersides of leaves. When a gall is split open, a yellow to orange nymph is visible. Leaves may be disfigured when infestations are heavy.
The adults of these insects are tiny and resemble miniature cicadas. They are dark reddish-brown with mottled wings. Most emerge from the galls during warm days in the fall and are very annoying as they gather around window screens seeking entry into the house. They are tiny enough to crawl through the openings in most screens. These are difficult insects to control. In the spring, the adults become active about the time the leaf buds open. The female lays her eggs on the underside of the developing leaves. Egg hatch occurs in 7 to 10 days and the young nymphs begin to feed immediately. The leaf reacts to the feeding by producing a pouch or gall that entirely encloses the nymph. Nymphs pupate in the fall and adults emerge in September.
Recommendations:
Psyllid control indoors: A vacuum cleaner with hose attachment may be used to remove invading psyllids. A space spray may be applied using a household aerosol labeled for flying insects. Use a product containing synergized pyrethrins or one of the pyrethroids (various names, but they usually end with -thrin). Note, not all aerosols are intended for flying-insect control. Read and follow label directions closely.
Preventing entry: Several steps can be taken during the fall just before frost to reduce entry. Turning off outdoor night-lights and reducing the amount of light shining through night windows helps. Consider using fine mesh (18) screens on windows that are kept open. Ordinary screens are 12 mesh to the inch. Caulk or plug up cracks and crevices. Keep windows and doors closed when psyllids are active. For temporary reduction, spray exterior surfaces such as window screens, shutters and sides of buildings where psyllids are resting. Look for residual insect sprays labeled to use on outdoor surfaces. Examples of ingredients with residual action include cyfluthrin, bifenthrin, permethrin, Baygon and tralomethrin.
References:
1. Life Histories of Common Insects, Mites and Nematodes Infesting Ornamental Plants in Missouri, Missouri Department of Agriculture, Plant Industries Division, pg J-7
2. Insects and Mites Associated With Shade Trees and Woody Ornamentals, pg 26, K-State Research and Extension Pub S-85
3. Hackberry Nipplegall Maker, K-State Research and Extension, Entomology Publication MF-957
Last Update: 10/22/2004
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