Asparagus Beetle Crioceris asparagi
The Asparagus Beetle is a rather small beetle, measuring only 6 mm. But its bright colours make it a very outstanding species. The neck shield is red, the shields are blue with a red fringe. On the shields are six rather rugged white patches, very variable in size. The colours of course are intended to warn certain enemies. And they work, for birds will not eat the beetles. The larvae are less pretty: they look like grubs and are grey. The first adult beetles appear by the end of April. They deposit their eggs, which will hatch in just a week's time. The larvae grow extremely fast and are full grown in less than two weeks. They drop from the host plant and dig a small hole in the underground, or crawl in leaf litter to pupate. Pupation doesn't take long either and soon the second generation of adults appear. Dependant on conditions there are two or three broods in one year. The last brood does pupate very quickly as well, but the adults stay in their hiding place to overwinter. This species only eats asapargus.
A moderate population of the Asparagus Beetle will make a crop less valuable. Infested plants stay small and look poor. When populations are big however, the beetle may consume the plant entirely. A natural enemy has been used succesfully: the parasitic wasp Tetrastichus asparagi. The wasp lays her eggs in the eggs or larvae of the beetle. It will not however reduce the number of adults once present. The Asparagus Beetle is very common, both in the temperate zones of Europe and of Northern America.