Vine weevil is a common and widespread pest, primarily of pot plants, although plants growing in the ground can also be attacked. The most serious damage is caused by the larvae which live in the soil and eat roots, weakening growth and often ultimately killing plants. Adult beetles eat small notches in leaf edges, although this tends to be disfiguring rather than severely damaging.
Why is vine weevil a problem?
The vine weevil larvae live amongst and eat plants’ roots. The first time you notice a problem may be when the plants wilt, collapse and die. By then it's too late for your plants, and the vine weevil can be well established.
What do vine weevil look like?
Vine weevil larvae are creamy-white with brown heads, ‘C’ shaped, and up to 10mm long. Adult beetles grow up to 9mm long, are dull black in colour, and are mainly active at night. Their eggs are round and measure less than 1mm, so are hard to spot in soil.
What are the symptoms of vine weevil?
At first you may notice irregularly shaped notches on leaf margins, particularly on evergreens such of rhododendrons and camellias. After this, look for sick or wilted plants – give them a gentle tug to see if the roots have been eaten, or you can carefully tip them out of their pots to examine the roots. Vine weevil larvae tend to be most active from autumn to spring but can be found all year round.
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Which plants are more susceptible to vine weevil damage?
Vine weevils attack a wide range of plants but they particularly favour primulas and polyanthus, cyclamen, fuchsias, strawberries and heucheras. Even if you don’t grow these plants, it’s worth placing several of them around the garden to act as an ‘early warning’ system. Examine them regularly for signs of infestation and you’ll know when to take action.
How do I control vine weevil without chemicals?
Adult vine weevils can be caught by hand and squashed – either inspect plants at night by torchlight when the beetles are active or shake pot-grown plants over newspaper
Encourage wildlife, such as toads and birds, which will predate on the beetles and their larvae
Buy and apply a biological control to control the larvae. A biological control is the use of a specific organism to kill a pest: in this case, several species of predatory nematode. These microscopic creatures are supplied in a small packet of a powdery substance which is mixed with water and poured onto the soil. Conditions must be sufficiently warm for the nematodes to be effective and also the vine weevil must be present: nematodes can’t be used as a preventative measure. The best time to apply outdoors is late summer to autumn.
Buy a trap for the adult beetles which is baited with nematodes. This is suitable for summer use only.
Sticky traps can be used to catch the adult beetles, but bear in mind they can trap other insects, and sometimes birds and mammals, too.
Advice on buying vine weevil killer
- Nematodes should be applied at certain times of the year, with soil temperatures above 5ºC only. Make sure you have the right conditions before buying
- Pesticides, particularly systemic pesticides like vine weevil killer can harm bees. make sure you only apply this if absolutely necessary and only to pots. Remove any flowers from the plant for up to two months after applying the pesticide, to ensure bees don't ingest it
Where to buy vine weevil killer
Is there a chemical control for vine weevil?
The systemic insecticide acetamiprid can be used only on ornamental plants growing in containers. Don't use it on edible plants, or ornamentals growing in the ground. Be aware that this chemical belongs to the group of chemicals known as neonicotinoids, which have been widely in the news for the adverse effects they have on bees.