Asparagus beetle is the most serious pest of asparagus. It only attacks edible asparagus – it doesn’t affect ornamental asparagus plants.
Both the distinctive adult beetles – black with six yellowish blotches and a reddish body, measuring 6mm (¼in) long – and the greyish-black larvae up to 1cm (3/8in) long feed on asparagus plants.
The adult beetles emerge from where they have overwintered from May to June, mate and the female adults then lay small black eggs on both asparagus spears and foliage. The resulting larvae feed on the plants until fully grown. They then drop to the ground and pupate in the soil.
There are usually two generations of adults and larvae per year between May and September.
In autumn, the second generation of adult beetles, move away from the plants to find a sheltered place to overwinter.