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Raspberry Beetle

AgriSense BCS Ltd © 2007 - Pest Image - Raspberry Beetle

Pest Status:
The Raspberry Beetle, Byturus tomentosus, is a serious pest of field and tunnel grown Raspberries, and sometimes Loganberry and Blackberry.  Female adults (3-5mm long, brown, covered with short light brown hairs), are attracted by the colour and smell of host flowers, feeding then laying eggs (1.5 x 0.4mm, shiny, cream-white) on their preferred hosts, raspberry and blackberry.  The larvae (up to 8mm long, pale yellowish brown, brown head and well developed thoracic legs) feed on ripening fruits and sometimes damage buds and shoot tips.  They burrow into the berries to feed on the plug and often go undetected until the mature fruit is picked.  Sometimes localised segments of attacked berries become shrivelled, hard or distorted as a result of the larval feeding.

Adult beetles can cause damage early in the season by feeding on blossoms, buds or new leaves of host plants.  This rarely causes serious problems unless beetles occur in large numbers, in which case significant crop losses and poorly developed, malformed fruits may result.

Generations:
There is usually 1 generation per year in field grown crops.  Adults emerge in April to early June but can be earlier in tunnel covered crops.  With warm weather (>13°C) the beetles mate from early June and in June/July eggs are laid in flowers.  The cultivation method and local climate will affect emergence times and duration of attack.

Trapping Season:
The traps should be placed in the field before the first beetles normally appear, generally 4 to 6 weeks before first flower in open-field raspberry crops and the traps maintained until at least the end of the flowering period.  This is normally between April and July but can be extended in protected cropping systems or with autumn fruiting varieties.  Where the crop has an extended flowering and fruiting season, it would be beneficial to continue to trap beetles during the fruiting period.  It should be noted that the exact time of insect emergence will vary with location and seasonal variation.