The grubs feed in the fruit receptacle or carpels and may end up as contaminants in the harvested berries. The adults chew holes in unfolding leaves and in flower buds. Damaged leaves look skeletonized or tattered, while damaged flower buds result in distorted berries, reduced fruit set, or premature fruit drop. Many flowers and fruit can be destroyed by this insect.
Early fruit is more at risk of attack than late fruit.
When viewed through a magnifier, dense hairs can be seen on their backs. The immature or larval forms, called grubs, are yellowish white with a light brown section on top of each segment, and a light brown head. Raspberry fruitworms overwinter as pupae in soil around brambles. Eggs hatch in a few days. Larvae tunnel into the flower receptacle to feed, then into the center of developing fruits.