Coleoptera: Curculionidae, Anthonomus signatus Say
The strawberry weevil is mainly a pest of the Coastal Plain but may be found wherever strawberries or dewberries are important crops. It appears every year and, when numerous, it greatly reduces the crop. It can breed also on wild dewberries and, to some extent, on blackberries and a few other wild plants.
The damage caused by the strawberry weevil is confined to the destruction of flower buds. Injured buds will be found hanging down with the stems almost severed near the bud. Damaged buds dry and turn brown before they fall to the ground. This characteristic damage has resulted in the strawberry weevil being referred to as the "clipper."
Strawberry weevils spend the winter hibernating in woods or thickets near the places where they were plentiful the previous spring. With the first warm days, about late March or early April, they start feeding on flowers or young leaves of wild plants and migrate to fields of strawberries or dewberries.
The strawberry weevil resembles the cotton boll weevil in shape. The entire insect, including the long snout, is only an eighth of an inch long.
The female weevil chews a hole with her mouthparts through the side of a bud. When the hole is sufficiently deep, she reverses her body and deposits an egg in the hole. Before going to another bud, the weevil cuts a deep notch in the stem an eighth to a quarter of an inch below the bud. The bud remains hanging for a few days but eventually falls to the ground. The egg hatches in about a week and the small grub feeds on the pollen. Later it transforms to an adult weevil within the dry bud. New adult weevils emerge during May and June and feed for a while on the flowers of blackberry and other plants. So far as is known, there is only one generation a year.
Strawberry weevil occurrence is sporadic. Considerable variation in damage occurs from year to year and from location to location. Though the reasons for this sporadic appearance of the weevil are not known, it is believed to be due to control by natural enemies.
Strawberry beds should be located some distance from woods and blackberry or dewberry thickets which provide an overwintering site and wild hosts. Likewise, beds should be free of grass, weeds and moss. Profusely flowering strawberry varieties and pistillate varieties appear to be less subject to attack by weevils.
The strawberry weevil can be controlled by spraying or dusting with an insecticide. Sevin or malathion is suggested. Be sure to follow label directions. Applications should begin when cut buds are first observed (check side of field nearest woods). Applications should continue through the unopened bud period as long as damage persists. As weevils feed during the day, early morning applications have proven to be more effective.
THE USE OF TRADE NAMES IN THIS PUBLICATION DOES NOT IMPLY ENDORSEMENT OF THE PRODUCTS NAMED OR CRITICISM OF SIMILAR ONES NOT MENTIONED.
Kenneth A. Sorensen