Asparagus Beetle
Pest · Commonly affects: Asparagus, Ornamental asparagus, Asparagus fern, Garden asparagus seedlings
Asparagus beetle can make an established asparagus bed look untidy and reduce the vigour of the fern that feeds next year's spears. It is chiefly a problem after harvesting, when adults and grubs feed on the developing foliage. Regular hand removal is realistic in a small garden and helps prevent a persistent population in the bed.
How to identify it
Adults are narrow, black beetles about 6-8 mm long, with cream patches and reddish markings on the wing cases. Their larvae are soft, grey-black grubs with dark heads, up to about 10 mm long, and may carry a coating of droppings. Look along young stems, fern and flower buds from late spring onwards. Orange-brown eggs, about 1-2 mm long, are laid in rows on spears and stems.
Damage
Adults chew notches in spears and foliage, while larvae strip soft fern and buds. Minor damage after the cutting season is usually cosmetic, but heavy repeated feeding reduces fern growth and the energy stored in crowns. This can mean weaker, fewer spears in following springs. Feeding also makes young plants slower to establish.
Prevention
Inspect asparagus regularly after spear harvesting ends, when foliage is allowed to grow. Keep the bed weed-free and well mulched with garden compost so plants remain vigorous. Do not leave old asparagus fern standing through winter: cut it down once it has died back and remove it from the bed. Avoid carrying volunteer asparagus seedlings between sites, as they can harbour beetles.
How to manage it
Hand-pick adults and grey-black grubs every few days, placing them in soapy water. Rub off rows of eggs found on stems before they hatch. If a young planting is badly affected, remove the most infested fern shoots while leaving healthy growth to feed the crowns. In autumn, clear all dead fern and surface debris, then inspect again in spring as new spears emerge.
Asparagus Beetle: frequently asked questions
How do I identify asparagus beetle?
Adults are narrow, black beetles about 6-8 mm long, with cream patches and reddish markings on the wing cases.
How do I prevent asparagus beetle?
Inspect asparagus regularly after spear harvesting ends, when foliage is allowed to grow.
How do I get rid of asparagus beetle?
Hand-pick adults and grey-black grubs every few days, placing them in soapy water.
General guidance for UK home gardens and allotments, focused on prevention and non-chemical control. For a confirmed diagnosis, the RHS or a local garden centre can help. Page updated 19 Sep 2026.