Raspberry Beetle

Symptoms by part

Causes

• Overwintering in the soil near the base of the plants.
• Warm weather during the flowering stage that encourages adult beetle activity.
• Presence of nearby wild brambles that act as a reservoir for the pest.

Could be confused with

• Spotted Wing Drosophila · This fly lays eggs in ripening fruit, causing it to collapse into a soft, mushy mess, whereas beetle larvae are usually found inside the core of firmer fruit.
• Raspberry Midge · Midge damage typically appears as splitting or peeling bark on the canes, rather than damage to the fruit itself.

Treatment

1. Place a white sheet under your bushes in the early morning and gently shake the canes to dislodge adult beetles, then collect and dispose of them.
2. Install fine mesh netting over the plants as soon as the first flowers open to prevent adult beetles from reaching the blossoms.
3. Pick all ripe fruit promptly to prevent larvae from exiting the berries and dropping into the soil to pupate.

Without chemicals

• Use fine mesh insect netting to physically block beetles from accessing flowers.
• Clear away weeds and debris from around the base of the plants to reduce overwintering sites.
• Cultivate the soil lightly around the base of the canes in autumn to expose pupae to birds and cold weather.

Chemical options

• Spinosad, apply as a spray to the foliage and flowers when beetles are active, follow the label.

Preventing it

• Keep the area around your berry patch free of wild brambles.
• Rotate your berry crops if possible to avoid planting in the same soil where beetles have previously pupated.
• Use physical barriers like netting every year starting at the first sign of bloom.

When to act

Take action as soon as the first flowers appear on your plants to prevent egg laying. If infestation levels are consistently high despite your efforts, consider replacing the plants with new, certified pest free stock.

Questions people ask

Are the berries safe to eat if I find a larva?

While it is unpleasant, the fruit is not toxic. Most people simply soak the berries in salt water for a few minutes, which causes the larvae to crawl out, then rinse the fruit well before eating.

Do I need to remove the whole plant?

No, the raspberry beetle does not kill the plant. It only affects the fruit, so you can manage the population through netting and regular harvesting.

Plants it affects

• Blackberry