This post concludes our look at Vine Weevils and how to get rid of them…
Prevention & Control
• Check regularly the leaves of susceptible plants
• Never buy or accept plants showing the tell-tale serrated bite marks
• Check the roots of any new plants when replanting
Natural & Biological
• Just as gardeners particularly attached to their Hostas will go on regular torch-lit slug hunts, so do those with vine weevils. Mild evenings in spring and summer are the best times to catch adult weevils. Smaller containers can be lifted upside-down and shaken over newspaper, an upturned umbrella or other receptacle. During the day, check under pots, shelves in greenhouses and other similar paces where the adult beetles may be hiding. They can also be trapped with readily-available sticky insect barriers
• Gardening with wildlife in mind is not just altruistic – if you don’t fancy midnight bug hunts, then let the birds, frogs, toads, shrews, hedgehogs and predatory ground beetles (etc.) you’ve encouraged into your garden do the work for you. The well-managed undergrowth of your hedge (click here for advice and to see how simple it is) will provide a home for an army of volunteers to patrol your garden.
• Introducing microscopic pathogenic nematode is an increasingly popular – and often effective – biological control against the larvae.
Two species are commonly used and applied in August and early September: Steinernema kraussei is effective from 5-20ºC and the more temperature sensitive Heterorhabditis megidis (12-20ºC). Both can be applied to garden soil but neither is effective if it is either dry or heavy. They work best in all types of potting compost and can be applied safely to all plants. They are available from specialist suppliers.
• There is no safe chemical treatment for edible plants
• Container-grown ornamentals can be treated in mid- to late-summer with proprietary insecticides containing either acetamiprid (effective for two months) or thiacloprid (a liquid drench effective for four months)
NB: Stay vigilant even if the treatment appears to have worked – vine weevils are resilient.