Vine weevils: how to protect plants against this garden pest

The vine weevil is a tiny root-eating grub capable of devastating damage underground. It can cause plants to yellow, wilt and eventually keel over as the last roots have been gnawed through.

If you think you’ve got vine weevil in the garden take action now to safeguard your plants from this pernicious pest.

What do vine weevils look like?

Adult vine weevils are black and about 1cm long. They lay eggs in soil from March to September, which hatch into white, C-shaped grubs that feed voraciously.

How to spot vine weevil damage

You know you’ve got vine weevils in the garden if you spot small, irregular notches around the outside of leaves. This is caused by adult beetles, which mainly feed at night on a whole host of plants including euonymus, bergenia and hydrangea. This damage is largely cosmetic, rather than life threatening to plants.

Plants grown in pots are vulnerable to vine weevil grubs, which eat roots beneath the soil. You often won’t realise there’s a problem until the plant topples over due to all its roots being severed.

Cactus, succulents, cyclamen, begonia, heuchera and many other plants are open to attack.

Where to find vine weevils

Vine weevil adults can often be found hiding under the base or lip of pots, so check regularly and squash any you find. Another technique used by some gardeners is to go out at night with a torch and shine it on the leaves of vulnerable plants, where you might spot the beetles feeding.

Adult vine weevils love to lurk under debris, so pick up fallen leaves and sweep up in the greenhouse to reduce the number of places they can conceal themselves.

Chemical control of vine weevils

Protect your pots by drenching the compost with a pesticide, Bio Provado Vine Weevil Killer 2. It can be mixed with water and applied with a watering can, protecting plants for up to four months.

The product is widely available from garden centres and can be used on pots all year round.

Biological control of vine weevils

If you don’t want to use chemicals, try Nemasys Vine Weevil Killer. This contains microscopic creatures called nematodes that are a natural enemy of vine weevils. The product is available from some garden centres, but has to be kept it in a fridge.

Pop it into a watering can, mix with water and sprinkle it on. This can be used for protecting pots or other parts of the garden. It can be used in greenhouses all year round, but is best applied in early spring or autumn outside.