Common Asparagus Beetle

Crioceris asparagi — the common asparagus beetle — is one of about 30 species in genus Crioceris (small leaf beetles in family Chrysomelidae, sister genus to the scarlet lily beetle Lilioceris already in the Wild Files). The species is native to Europe and was accidentally introduced to North America in 1859 (first detected in New York via imported asparagus crowns), then spread across NA asparagus-growing regions over the past 165 years. The species is now widespread across all of North America and Europe wherever cultivated asparagus is grown. Adults are 5-6 mm long, with the species' diagnostic features: brilliant METALLIC BLUE-BLACK ELYTRA marked by THREE CREAM OR YELLOW SQUARE SPOTS BORDERED IN RED — the spot pattern creates a striking visual signature that is unmistakable in the field. Larvae are gray-green humped 'slug-like' grubs with darker head capsules. The species attacks ASPARAGUS (Asparagus officinalis) — the only known host plant for the species' larvae — feeding on asparagus spears (the edible young shoots harvested in spring), young foliage, and developing seed pods. Larvae develop on asparagus foliage over 2-3 weeks and pupate in the soil. The species causes significant damage to asparagus production: defoliation reduces plant vigor and reduces next-year spear production; spear damage by adults reduces fresh-market quality. The species is the foundational pest of asparagus production worldwide and is featured in essentially every modern textbook discussion of asparagus pest management. The species shares the FECAL SHIELD DEFENSIVE BEHAVIOR with its close relative the scarlet lily beetle (Lilioceris lilii — see Wild Files). Asparagus beetle larvae cover themselves in their own MOIST FECAL EXCREMENT to create a wet brown coating that hides the gray-green larval body and creates a repulsive appearance that deters bird and small-mammal predators. The fecal shield defense is shared across multiple Chrysomelidae genera and is one of the most-cited examples of evolutionary convergence on excrement-based defense in herbivorous beetle larvae. The species is harmless to humans (no bite, no sting) but is the major pest of asparagus production worldwide.