Pear Thrips on Forst Trees

United States
Department of
Agriculture

Forest Service

Northeastern Area

NA-FB/P-34 Revised 5/89

Pear Thrips on Forest Trees
The pear thrips, Taeniothrips inconsequens (Uzel), an imported species first noted in California in 1904 and now throughout the United States, is a common thrips found on many plants, but particularly fruit trees. Pear thrips have been considered a serious forest pest onlly recently (1979, when they, along with Thrips calcaratus Uzel, caused widespread defoliation in Pennsylvania). Infestations of forest trees have been reported from New York, Pennsylvania, and all of the New England States.

The adult pear thrips are tiny (less than 2 mm long), slender, dark brown, and have long, narrow wings coverd with a hairy fringe. Immature stages are white with red eyes and wingless. Around mid-June, the thrips enter the soil as larvae where they mature and overwinter in the soil. They emerge in early spring to feed on swollen buds and expanding leaves and to reproduce. Eggs are laid in the leaf epidermis, mainly of veins and petiole, leaving brown scars.

In forest stands, maples (especially sugar maple), birches, ash, black cherry, and beech are all affected. Other forest trees may be affected as well. Symptoms include fallen green leaves, leaves smaller than normal, cholorotic and tattered leaves, leaf margins, frequently browned or wilted, and leaves puckered or wrinkled. Where the outbreak has persisted longest, growth decline and crown dieback have occurred.

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Figure 1. Maple leaves injured by pear thrips.

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Figure 2. Adult pear thrips on sugar maple bud.

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Figure 3. Maple leaves injured by pear thrips. Note oviposition scars on veins and petiole.

Authors:

James O'Brien and Parker Snowden, USDA Forest Service

Photo credits:

1. Margaret Miller-Weeks, USDA Forest Service

2. Pennsylvania Bureau of Forestry

3. Ron Kelley, Vermont Department of Forests, Parks, and Recreation

For additional information, contact:

USDA Forest Service
Forest Health Protection
180 Canfield Street
Morgantown, WV 26505
(304) 285-1541 USDA Forest Service
Forest Health Protection
271 Mast Road
Durham, NH 03824-0640
(603) 868-7704 USDA Forest Service
Forest Health Protection
1992 Folwell Avenue
St. Paul, MN 55108-1099
(612) 649-5261