The common asparagus beetle (Crioceris asparagi) is a widespread and important pest of commercial asparagus crops ( Asparagus officinalis) in Europe and North America. Both the larva and the adult feed only on asparagus plants; both phases cause considerable damage. In addition to damaging the spears by feeding directly on them, the larvae and adults both feed on the fern, which can reduce the productivity of the plant to form spears in subsequent years by reducing its ability to photosynthesize and store energy. The soft, grey larvae feed for about two weeks until they reach their mature length of 6-7 mms and drop to pupate in the soil below. The adult beetle is bright blue and brown with cream-colored spots. Crioceris asparagi generally undergo two generations per year. Crioceris asparagi overwinters as the adult beetle. Early in the spring the beetles emerge from diapause in the leaf litter to start eating and to lay 2mm dark greenish-grey eggs, usually in clusters of 8-10, up and down the asparagus spears. These sticky and difficult to remove clusters are another means of damage by which C. asparagi reduces a crop’s marketability.

Various insecticides are licensed for control, and the parasitic wasp Tetrastichus asparagi Crawford has been successfully used for biological control.

The closely related spotted asparagus beetle (Crioceris duodecimpunctata
) has a similar distribution throughout Europe and North America and also feeds on asparagus (as well as Cucurbitaceae). The two beetles are easily distinguished; C. asparagi are orange-red with black spots. Unlike the common asparagus beetle, C. asparagi do not cause significan damage to asparagus crops because: 1. the cream colored larvae mature and feed only inside the asparagus berries and 2. adults lay eggs only on asparagus ferns, not on the spears. Planting male only asparagus strains, which do not produce berries, removes the threat of the spotted asparagus beetles as a pest.

(University of Illinois extension, 2011; Fraval 1997; Watts 1912; Wikipedia 2010; Wikipedia 2011; Witt and Edwards 2002)