Collection: Control the black vine weevil

What is the black vine weevil?
The black vine weevil is black in colour and has a grooved black shell with yellow marks on the wingcases. Adult weevils are only active at night and take round bites from the edges of leaves. During the day, they shelter under dry leaves at the bottom of bushes and shrubs. The larvae of the black vine weevil look like grubs, but have no legs. 

What damage do black vine weevils cause?
You can recognize damage caused by a black vine weevil from the round bites from the edges of leaves. The damage is caused by adult weevils. The larvae of the black vine weevil feast on the roots of plants. This can cause younger plants in particular to die, but also makes older plants more vulnerable to fungus and disease.

The lifecycle of the black vine weevil
In the UK, adult black vine weevils lay their eggs between May and November, depending on when it turns colder. After eight to 20 days, the larvae emerge from the eggs. After feasting on the roots of plants for around nine months, the larvae develop and pupate, becoming adult weevils, which then lay new eggs before dying, usually before winter. Adult black vine weevils can survive milder winters and in greenhouses.

Managing the black vine weevil with nematodes
You can use nematodes against the larvae of the black vine weevil. Management is most effective if the larvae are still small, but because the adult black vine weevil continues to lay eggs for several months, there will also be larvae of different sizes. It’s therefore a good idea to use nematodes twice a year – the first application should be in August to catch larvae that emerged in the spring and early summer, and the second application should be towards the end of October or November to manage later larvae. If you have a stubborn infestation, you can also use nematodes in the early spring before the larvae being to pupate.

Which nematodes are most suitable for use on black vine weevil larvae?
Heterorhabditis bacteriophora and Steinernema feltiae are both excellent at combating the larvae of the black vine weevil. We recommend Steinernema feltiae for soil temperatures below 16°C, and Heterorhabditis bacteriophora for soil temperatures above 16°C. When autumn arrives, don’t wait for too long before applying the nematodes, as Steinernema feltiae is less effective when soil temperatures fall below 8°C.

Click here for the instructions for use