Asparagus Beetle

The asparagus beetle is a small leaf beetle specialized almost entirely on asparagus, where both adults and larvae feed on spears, ferny foliage, and berries. Its striking coloration, a dark metallic body set off with pale cream squares and a reddish margin, makes it one of the more easily recognized garden beetles once spotted.

Adults overwinter in plant debris and become active as soon as asparagus spears begin emerging in spring, often being one of the first visible pests in an asparagus bed each season. Feeding scars and blackened, scarred spear tips are frequently the first sign of activity before the beetles themselves are noticed.

A related species, the spotted asparagus beetle (Crioceris duodecimpunctata), is orange with black spots and often found alongside the common asparagus beetle, though its larvae feed mainly inside the berries rather than on foliage.

• Body elongate-oval, about 1/4–3/8 in (6–9 mm) long, with a metallic blue-black head and wing covers
• Wing covers marked with cream to yellowish squares bordered by a reddish-orange margin
• Thorax reddish and narrower than the wing covers, giving a distinct waisted appearance
• Antennae short and thread-like
• Larva is a soft, plump, dark gray to olive grub with a black head, often seen feeding openly on ferny asparagus foliage
• Lookalike: the spotted asparagus beetle, which is orange-red with twelve black spots rather than cream squares

Found wherever asparagus is grown as a garden or farm crop, primarily across temperate North America and Europe. Adults become active in spring as soon as asparagus spears emerge and remain present through the growing season into the fern stage, overwintering as adults in hollow stems, mulch, or garden debris.

Both adults and larvae feed on asparagus tissue: adults chew on spear tips, stems, and the feathery foliage that develops after harvest, while larvae feed mainly on the ferny growth. Adults also lay dark, cigar-shaped eggs standing on end along spears and stems. As a specialist herbivore, the species has little ecological role outside of asparagus plantings but is preyed upon by various generalist predators such as lady beetles and predatory bugs that target its eggs and larvae.

Development is complete metamorphosis, with several generations possible in a single growing season in warmer climates. Eggs are laid in rows on spears and foliage and hatch within about a week; larvae feed for roughly two weeks before dropping to the soil to pupate in a small earthen cell. Adults emerge in one to two weeks and continue feeding and laying eggs, with the final generation of adults overwintering in sheltered plant debris until the following spring.