Raspberry beetle

What is raspberry beetle?

Raspberry beetle causes damage in its grub stage, which feeds at the stalk end of the fruits. It is mainly a problem on summer-fruiting raspberries. Early fruits on autumn raspberries may be damaged, but those ripening after late August are less likely to be affected.

Symptoms

• Damaged ripe berries have greyish-brown dried up patches  at the stalk end
• A brownish-white grub, up to 8mm (about1/4in)  long, may be found inside the fruits

Control

Chemical control

• Pyrethrum (Py Spray Garden Insect Killer, Bug Clear Gun for Fruit & Veg, Doff All in One Bug Spray) can be used to control raspberry beetle. A minimum one day interval  is required between spraying and picking the fruit
• A better level of control is likely to be achieved with deltamethrin  (Bayer Sprayday Greenfly Killer), which has a seven-day harvest interval on cane fruits
• Spray raspberries when the first pink fruits are seen, with a second application two weeks later
• Treat hybrid berries at 80% petal fall and blackberries when the first flowers open
• Apply insecticides in the evening when bees are not active on the flowers
• Derris/rotenone is no longer available for use as a garden insecticide

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Links

Chemicals: storing and disposing safely

Biology

• The 4mm (about 1/8in) long adult beetles are pale brown and they lay eggs on the flowers in May to mid-July
• The young larvae feed at the stalk end of the developing fruit, but later move inside to feed on the central plug
• In late summer, the fully-fed larvae move into the soil where they overwinter as pupae