Raspberry beetle (aka Western raspberry fruitworm)
Byturus unicolor
0 host plants
Last updated
Small yellowish-brown beetles 4-5 mm long feed on black raspberry buds and emerging leaves in late April and May, creating characteristic slits between leaf veins. Infested blossoms develop into misshapen or stunted berries. Larvae tunnel into young fruit and feed on the receptacle for 30 days, causing fruits to shrivel, drop prematurely, and become unmarketable.
Adult beetles overwinter in the top 3 inches of soil and emerge as temperatures warm. Inspect buds and new growth for damage; prune off heavily infested shoots. For commercial plantings, insecticide applications at early bloom protects developing fruit. Home gardeners can tolerate cosmetic damage.
Quick Reference
The adult is a small yellowish brown beetle 4-5 mm in length. The larvae are 8 mm in length; white with brown areas on the back of each segment. Adults feed on fruit buds and unfolding leaves. This injury can be serious in the spring. After the flowers open, the beetle feeds on the stamens and pistils. Injured blossoms often turn into distorted berries. The larvae enter the young blossoms or fruit and feed on the receptacle. The larvae often remain in the fruit at harvest, and represent a...
Cultural Controls
- Handpick and destroy adult beetles when practical. Adults are most active in early evening.
- Adults tend to drop from the plants when disturbed; catch them by placing a beating tray under the plant and tapping or shaking the canes vigorously.
- For best results, beat in the morning or evening when the air is cool.
- Maintain good weed control in and around plantings, particularly wild brambles that serve as alternate hosts.
- Cultivating around plants in late summer to early fall may kill larvae and pupae and reduce the number of adults emerging in spring.