integrated pest management

Strawberry Clipper
Anthonomus signatus

The strawberry clipper, Anthonomus signatus, also known as the strawberry weevil, is a dark, reddish-brown weevil about 1/10 inch long; its head is prolonged to form a slender, curved snout about 1/3 as long as the body. Adults overwinter primarily in fence rows and wood lots (although a small portion of a population may remain in the strawberry field), then move to plants with developing fruit buds. The seasonal timing of strawberry flowering coincides with clipper movement from overwintering sites, so strawberries are ideal host plants for this insect.

Strawberry clipper (aka strawberry weevil) Adult is 1/10 inch (2.5 mm) long.

Strawberry Clipper

Adult clippers first feed on immature pollen by puncturing nearly mature blossom buds with their snouts. The female then deposits a single egg inside the bud and girdles the bud, preventing it from opening and exposing the developing larva. The adult female then clips the stem so that the bud hangs down or falls to the ground. Larvae feed within the damaged bud for a period of 3 to 4 weeks; a new generation of adults emerges in late June and July. These weevils feed on the pollen of various flowers for a short time, but seek shelter in midsummer in preparation for overwintering.

Strawberry Clipper damage

An illustration of the damage caused by strawberry clippers early in the season

Because the strawberry clipper does not disperse over long distances, locating strawberry plantings away from wood lots and hedge rows that harbor this insect through the winter reduces the number of adults that move into strawberries in the spring. Because earliest varieties are usually damaged more than later ones, planting 2 or 3 rows of an early variety as a trap crop around the perimeter of each field has been suggested as a way to reduce overall damage or to "concentrate" adults for control by use of an insecticide.

Integrated pest management guidelines for strawberries in Massachusetts (Cooley & Schloemann 1994) recommend sampling for strawberry clipper adults and damage as soon as flower trusses are visible in crowns. Look for clipped buds and adult weevils in unexpanded flower clusters. (This should be a close-up inspection -- hands-and-knees type of work.) Sampling should be most intensive along field edges near woods or hedge rows. One clipped bud per 2 ft. of row is enough to warrant an insecticide application for clipper control; limiting insecticide application to border rows may be adequate in many instances. If control is necessary, insecticides should be applied as soon as damage begins to occur, usually well before most flowers have begun to open. Check the most up-to-date edition of the Illinois Commercial Small Fruit and Grape Spray Guide for a listing of insecticides registered for clipper control.

References Cited

  1. Cooley, D.R., & S.G. Schloemann. 1994. "Integrated Pest Management for Strawberries in the Northeastern United States." Cooperative Extension Service, University of Massachusetts, Amherst.