Specieswatch: black vine weevils – a tiny menace to crops and ornamentals

There's new advice for gardeners on how to tackle this little beetle which doesn't involve pesticides

The first sign of black vine weevils, Otiorhynchus sulcatus, is usually when one of your favourite pot plant wilts and dies in the spring. The larvae, small creamy white sickle-shaped grubs, devour plant roots and then the base of the stems until the plant keels over. The grubs are a major pest in nurseries where there are many plants in containers. Out in gardens they attack many varieties of ornamentals including rhododendrons and camellias plus crops such as strawberries. Although outdoor attacks are seldom fatal they weaken the plants.

When adult beetles emerge in April they are only 10mm long and nocturnal. The adults cannot fly but can run fast and climb plants at night, feeding by taking bites out of leaves. By day they hide under any debris on the soil surface to avoid being eaten by predators which include birds, frogs, toads, shrews, hedgehogs and other beetles. In the autumn they lay eggs in the soil, the larvae then munching away unseen all winter.