Raspberry: Raspberry beetle (raspberry fruitworm)
categories: Raspberry Raspberry Insects Small Fruits
revision date: 2023-02-08 12:00
Photo by: T. Murray
Biology
Raspberry fruitworm (the larva) and raspberry beetle (the adult) are pests of raspberries and loganberries. The adults are yellow-brown beetles about 1⁄6″ long. Raspberry beetles overwinter in the ground as adults, emerging from the soil in the spring (typically April-May). Adults feed on developing leaves, flower buds, and flowers. They leave characteristic slits between the veins of unfolding leaves as they feed. Injured blossoms often develop into distorted or malformed berries. Eggs are laid on flowers, buds, or stems. Hatching larvae burrow into the center of developing fruits, feeding in the receptacle (core) and drupelets for a month or more. The larvae are white with brown patches on the back of each body segment. At maturity, they are about 1⁄3″ long. After the larvae finish feeding, they drop to the ground where they burrow into the top 3 inches of soil and pupate. If the fruit is harvested before the larvae drop, they remain in the fruit and are a significant contaminant of harvested fruit. There is typically one generation per year. Raspberry beetle also feeds and reproduces on wild blackberries, thimbleberries, and salmonberries.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Handpick and destroy adult beetles when practical. Adults are most active in early evening.
- Since adult raspberry beetles tend to drop from the plants when disturbed, they can also be caught by placing a beating tray under the plant and tapping or shaking the canes vigorously (being careful not to damage canes). The tray can be as simple as an old umbrella or cookie sheet, or a frame with a piece of light-colored fabric attached. Adults will drop onto the frame and can be captured. 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 the spring.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Monitor by scouting for the presence of adult beetles before flowers open.
- The best time to control this pest is prior to bloom.
- Larvae inside the fruit are not affected by chemical controls, so management must occur before they enter the fruit.
- Apply chemicals before eggs are deposited, when buds begin to swell and separate, and again just before blossoms open.
Approved Pesticides
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
Additional Image
Photo by: T. Murray