Hypera postica Gyllenhal A clover leaf weevil

Adults and larvae feed on the buds, leaves and seeds of various members of the Fabaceae, especially lucerne and trefoils. Young foliage becomes tattered and riddled with irregular holes, and flower buds are destroyed. The pest also causes distortion, discoloration and death of growing points. Attacks on seed crops are especially serious and usually most severe in dry seasons; in the British Isles they occur mainly in eastern England.

BIOLOGY

Adults hibernate in hedgerows and other sheltered situations, reappearing in March and April. After feeding for about 2 weeks, eggs are deposited singly or in batches in small holes bitten into

Fig. 232 A clover leaf weevil, Hvpera nigrirostris (x!8).

the stems of plants. Each female deposits 600800 eggs over a period of several weeks, and the eggs hatch 2-3 weeks after being laid. The larvae feed within the stem for a few days and then migrate to the shoot tips where they attack the buds. They feed externally (this is unusual for weevil larvae). Larvae are fully grown in 3 or more weeks, passing through four instars. They then pupate, each in a flimsy, yellowish-white, net-like cocoon formed on the host plant, usually on the underside of a leaf, or on the soil. Adults emerge about 2 weeks later; they feed briefly before seeking shelter in which to overwinter. In the British Isles, this species is univoltine; however, in southern Europe, and in other favourable regions, there may be two generations annually.

DESCRIPTION

Adult 4.5-5.5mm long and appear mainly greyish-brown, with paired, dark, longitudinal stripes extending dorsally down much of the body and narrowing posteriorly on the elytra; rostrum relatively broad and about half as long as the prothorax; prothorax often with a pale, narrow

Fig. 233 Larva of a clover leaf weevil, Hypera postica (x15).

dorsal line and a pair of pale subdorsal bands. Egg 1.0 x 0.5 mm, oval, yellowish to brownish. Larva up to 6 mm long; body greenish with a white dorsal stripe (Fig. 233); head brownish-black.

Building Your Own Greenhouse

Building Your Own Greenhouse

You Might Just End Up Spending More Time In Planning Your Greenhouse Than Your Home Don’t Blame Us If Your Wife Gets Mad. Don't Be A Conventional Greenhouse Dreamer! Come Out Of The Mould, Build Your Own And Let Your Greenhouse Give A Better Yield Than Any Other In Town! Discover How You Can Start Your Own Greenhouse With Healthier Plants… Anytime Of The Year!

Get My Free Ebook


Post a comment