Common Asparagus Beetle, Crioceris asparagi &
Spotted Asparagus Beetles, Crioceris duodecimpunctata
Both species of asparagus beetles occur throughout the U.S. and Canada wherever asparagus is grown. Asparagus is the only food plant of these beetles. The beetles eat shoots and leaves but are particularly damaging when they gnaw the tips of buds causing them to scar and turn brown. In dry seasons, asparagus shoots may be blackened by hundreds of eggs from these beetles.
- The common asparagus beetle is bluish-black with 6 cream-colored spots on its back. Eggs are dark brown, bullet-like, and 1.5 mm long. They are attached by one end to the host plant.
- The spotted asparagus beetle egg is greenish and glued on its side to the host plant. The adults are reddish-orange with 12 black spots.
The larvae of the common asparagus beetle damage plants much like the adults but also secrete a black fluid which stains the plant. Larvae of the spotted species, on the other hand, feed on developing berries, each larva often consuming three or four. Damage to the berries, however, is of little economic importance.
Asparagus beetles overwinter as adults in sheltered sites, particularly under bark or in stems of old plants. Common asparagus beetles appear slightly earlier in spring than the spotted species. The beetles feed as soon as they emerge and several days later egg laying begins.
Control begins with keeping a clean area where you grow asparagus. Remove weeds, dead and dying plant debris. This reduces where they can hide and protect themselves during winter. Other recommendations include:
- Scout and remove adults and eggs whenever possible. Place them in soapy water to drown.
- In spring, apply the beneficial nematode, Heterorhabditis bacteriaphora to the area.
- Generalist beneficials such as ladybugs and green lacewing are successful at controlling these beetles – in all life stages.
Control products are listed below. For more information please see our Pest Beetle Control page.