Blueberry Thrips
(Frankliniella vaccinii Morgan & Catinathrips kainos O'Neill)
Fact Sheet No. 202, UMaine Extension No. 2373 

Description

Thrips are very small (1/4-inch long) and difficult to see.  Uncurling the rolled up leaves of infested plants may reveal small, slender, yellowish to white thrips (Photo 1).  This problem is more readily identified by the presence of very tightly rolled-together leaves and twisted stems on blueberry plants beginning early in the season (late May or early June) (Photo 2).  Also, infested leaves often turn bright red and are quite conspicuous (Photo 3).

Life Cycle

Blueberry thrips winter in the soil as adult females.  They begin to emerge and feed on tender new plant material in May or early June.  Eggs are laid in developing leaf tissue and young, immature insects can be found within the curled leaves until late July or early August.  Eventually, the thrips mature into adults, leave the plant, and move back into the soil.

Damage and Economic Importance

Although thrips damaged plants can be found in crop fields, most economically important damage occurs in pruned fields.  Leaves infested with feeding thrips usually do not unfold properly.  The infested leaves remain tightly curled around the stem of the plant and fruit buds do not develop normally.

Damage is usually confined to small isolated patches that are heavily infested, while individual thrips injured plants may be found scattered throughout the rest of the field.

Pest Management

The blueberry thrips can be controlled with an appropriate pesticide; however, proper timing of applications is especially important.  Spot burning of infested areas may also be effective.  For additional information on monitoring and control, refer to Wild Blueberry Fact Sheets Nos. 204 and 209, or contact the lowbush blueberry specialist, University of Maine Cooperative Extension, 1-800-897-0757 (toll-free in Maine) or 207-581-2923.

Prepared by Judith A. Collins, Assistant Scientist, and H. Y. Forsythe, Jr., Professor of Entomology, in cooperation with David  Yarborough, Extension Blueberry Specialist, The University of Maine, Orono, ME 04469. November 1995.