Cranberry Fruitworm: Appearance, Territory, Damage and Life Cycle

Latin Name: Acrobasis Vaccinii

Appearance: The cranberry fruitworm is a North American native that has been identified as a pest of cranberry agricultural systems. These insects are the major pest of large fruit cranberries and a substantial problem of highbush blueberries as larvae. This pest hibernates as larvae in a hibernaculum. Moths emerge in late June and may be tracked using pheromone traps. Eggs are placed singly on the fruit, and oviposition can be delayed until the berries are of the proper size and color. Larvae penetrate the fruit shortly after hatching and can swallow up to six fruits during their growth. Long-lasting pesticides provide the most effective control.

Hosts Plants: The cranberry fruitworm’ s host range is restricted to berry-producing plants in the genus Gaylussacia, which includes black huckleberry and highbush blueberry. Adults do not feed on or harm host fruit; instead, females oviposit on the surface of these host fruits, and larvae eat entirely inside the fruit while it grows.

Territory: The cranberry fruitworm is native to North America.

Damage Insect Cause: Cherry fruitworm larvae infest only one berry and become active a week or so before cranberry fruitworm. Cranberry fruitworm is one of Wisconsin’s most problematic cranberry pests. The larvae solely eat inside within the apple. Each larva may consume 5-8 fruits. Significant crop loss can occur if unchecked.

Life History and Habits: Cranberry fruitworm spends the winter in the soil in the prepupal stage. Pupation takes place in early spring, with adults emerging from mid-June until the end of July. Peak flying happens around the time of flowering. The adults are nocturnal and spend the day amid the vines.

From June through early August, adult moths are active on calm evenings. They normally stay concealed amid the cranberry vines during the day, but data suggests that at night, they prefer to travel to neighboring trees for mating and then return to the cranberry beds before dawn. Moths have been observed flying long distances (270′ to 0.3 miles or more) in a single flight. The front wings are gray-brown with two tiny black spots at the front border. There are two white marks as well, one near the base of the front wings and the other towards the center of the front margin. The hind wings are gray-brown as well.