Crioceris asparagi L Asparagus beetle

This beetle is a generally common and important pest of vegetable asparagus; infestations also occur on ornamental asparagus and on Asparagus officinalis. Adults and larvae feed voraciously on the foliage; they also strip sections from the bark of the stems and branches, and contaminate host plants with black excrement. Heavily infested plants are defoliated, weakening the crowns and reducing yields.

BIOLOGY

Adults hibernate in sheltered situations, such as hollow stems or soil crevices, and become active in the spring. They then disperse to asparagus plants, where they begin to feed and where mating takes place. Eggs are deposited on the fronds in short rows from late June onwards. They hatch in about a week. The larvae feed for about 3 weeks, passing through three instars. They then pupate in the soil, each in a parchment-like cocoon formed a few centimetres below the surface. The next generation of beetles appears 2-3 weeks later. There are usually two overlapping generations annually.

DESCRIPTION

Adult 6-7 mm long; head shiny blue-black; thorax reddish, black-edged; elytra yellow and black, the former colour forming six pale spots and the latter a central band and three crossbands (Fig. 216). Egg 1.2-1.6mm long, elongate-oval with a flat base (Fig. 217a); greenish-grey, becoming darker close to hatching. Larva up to 8 mm long; body dark, greenish-grey, distinctly wrinkled and sac-like, with several short, fleshy abdominal prolegs, including a well-developed central proleg (pseudopod) on the anal segment; head, prothoracic plate and thoracic legs shiny black

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