Raspberry Fruitworm, Byturus
I. Introduction: Raspberry fruitworm was formerly considered to be two species, one eastern and one western (Byturus rubi Barber and B. bakeri Barber, respectively). These are now synonymized with Byturus unicolor Say (Springer and Goodrich1983). The adult is a small, somewhat hairy light brown beetle, about one-eighth inch long. Whitish larvae may be seen in harvested fruit.
II. Biology: After the pupae overwinter, adults emerge as raspberry leaves unfold in April, and are more active in the early evening. Adults first feed along the midribs of unfolding leaves. Watch for elliptical holes in foliage from adult feeding. As buds open, beetles will feed on the blossoms. Female beetles lay their eggs on or near blossom buds, and the hatching larvae enter the blossoms or small fruit. When larval development is complete, they drop to the ground (usually in July) where they pupate and spend the winter. Sprays may be applied in the early and late prebloom period.
IV. Control: It is helpful to maintain good weed control. Time chemical control applications to when fruiting buds first form and just before blossoms open. Entrust, carbaryl, malathion and Pyrellin may be recommended. See the Pest Management Guide for Commercial Small Fruit.