Name: Byturus bakeri

Alias: Raspberry beetle, or Western raspberry fruit worm. The adult is a small beetle that comes in various shades of brown. It is usually 4-5 millimeters in length. Adults spend their winter months in the soil, waiting for spring to emerge and lay eggs on the fruits, leaves and flowers of the plants. Larvae look like a tan worm or caterpillar and are almost twice the length of their adult form. They spend most of the larval stage feeding inside of the fruit. They produce one generation per year.

Crimes: Both the adult and larval stages feed on the plant, preferring cane fruits such as raspberries and blackberries. Adults feed on the buds and flowers in the early spring, causing the fruit to be disfigured or undeveloped. The larvae feed inside the fruit, causing contamination and rejection at the market.

Redeeming qualities: They can add a little bit of protein to your raspberry shakes this summer.

Sentence: The presence of one or two raspberry beetles may not be enough to merit control options. However, if large populations exist then it may be necessary to control them through other means. Carbaryl or a pyrethroid-based insecticide can prove to be effective while adults are still emerging and before they have laid their eggs, usually around the first of May. Always read and follow label instructions.

For more information on dangerous and beneficial bugs, call UI Extension educator Joseph Sagers at 208-745-6685 or email

Recommended for you