Family Byturidae

Byturus tomentosus (Degeer) Raspberry beetle

This beetle is an important pest of blackberry, loganberry and raspberry. The adults, if present in large numbers before blossoms open, can cause considerable damage to flower buds. Most significant damage, however, is caused by the larvae, which feed within the developing fruits and lead to the appearance of shrivelled, distorted fruits with numerous brown, hardened drupelets. The larvae may also contaminate consignments of fruit sent for processing.


Adults are active in sunny weather from May onwards. They often then feed on the open blossoms of fruit trees and other trees, especially Crataegus monogyna. Later, they migrate to raspberry and other Rubus hosts where they feed on the buds and open blossoms. Eggs are deposited in the flowers about a week later. The eggs hatch in about 10 days, usually during the green-to early pink-fruit stage. The larvae feed on the developing drupelets and also bore into the fruit plug. They become fully grown in about 5 weeks. They then enter the soil to pupate, each in a small earthen cell formed a few centimetres below the surface. The adult stage is attained by the autumn but the adults do not emerge until the following spring, individuals overwintering in situ. There is just one generation each year.


Adult 3.5-4.5mm long, brown, coated with a fine, yellowish-brown to grey pubescence. Egg 1.2 x 0.4 mm, creamish-white and shiny. Larva up to 8 mm long; body pale yellowish-brown, with darker dorsal tergites and with a pair of dorsal cerci on the penultimate abdominal segment; thoracic legs well developed; head shiny brown (see Fig. 69).

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