Black vine weevil

A weevil that attacks you garden and nursery plants? That could be the black vine weevil Otiorhynchus sulcatus. Adults and grubs also cause feeding damage in many berry crops. Are you ready to react to this pest with biological control?

What damage can black vine weevils cause?

• Adults feed at night producing notches around the edge of the leaves and flowers. However, grubs cause the most severe damage.
• Immediately after hatching, the black vine weevils start feeding on little roots. They also attack bigger roots, tubers, rootstocks and strip bark form woody stems as they grow.
• It can take a while before the damage is discovered. At that point, the plant is often already weak and starts to die. Damaged plants wilt and die.
• Plants that grow slowly and can’t compensate for lost root tissue often get damaged.

How to control black vine weevils?

For biological control of the black vine weevil, you can introduce the beneficial nematodes Kraussei-System.

What are the characteristics of black vine weevils?

• The eggs are 0.8 mm, round and white. As they grow, the eggs turn brown.
• Full-grown larvae are 10 to 14 mm, C-shaped, legless, cream-coloured with a shiny brown head and a soft body.
• Adults are 8 to 12 mm with a long and grooved, dull black shell with patches of tiny yellow spots.
• They don’t have wings, but walk and climb extremely well.
• You will rarely spot them as they are well camouflaged and only active at night.

What about the black vine weevil’s life cycle?

• Females hatch from unfertilized eggs as no males are spotted. Eggs hatch in 8 to 20 days.
• Immediately after hatching the females start feeding for 10 days and then start laying unfertilized eggs. Females lay up to 500 eggs.
• Tiny larvae burrow deep into the soil.
• Black vine weevils hibernate as larvae and pupate in spring when temperatures rise.
• You can find the pupae in cavities several centimetres down in soil.
• In spring, adults emerge from the soil 3 to 4 weeks after pupating.
• In greenhouses their life cycle is completed more rapidly as different stages can be spotted all year round.