Asparagus Beetle

Crioceris asparagi

The Asparagus beetle can be found throughout North America. The adults are small (¼” long) with six whitish spots; the larvae are small (1/3”) and slug-like. Both feed on the mature ferns of Asparagus as well as the emerging shoots (often causing them to become crooked). Asparagus beetles aren’t usually abundant enough to do serious damage and can usually be ignored by home gardeners (they are potentially more serious for commercial growers as blemished and crooked spears can’t be sold). If they get too numerous they can defoliate the leaves and weaken the plants.

Control

Adults may overwinter in leaf litter (or old asparagus stems) so if these beetles are a problem it’s a good idea to clean up your asparagus bed (some people leave the soil bare over the winter). The easiest remedy is to hand pick individual beetles whenever you see them (look for larvae and eggs too) and this can help ensure they don’t get out of hand. You could also protect the emerging spears with row covers. As always you should encourage predators.

The spotted Asparagus Beetle (Crioceris duodecimpunctata) is red with 12 black spots and is found in Eastern North America. It is rarely much of a problem.

Image:Whitney Cranshaw, Colorado State University, Bugwood.org