Common asparagus beetle
Encyclopedia
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
crops both in Europe and in North America. Asparagus is its only food plant. The beetle is about half a centimeter long, metallic blue-black in color with cream or yellow spots on its red-bordered elytra
Elytron
An elytron is a modified, hardened forewing of certain insect orders, notably beetles and a few of the true bugs ; in most true bugs, the forewings are instead called hemelytra, as only the basal half is thickened while the apex is membranous...
. The larvae are fat gray grubs with dark heads.
The adult beetles and the larvae strip the needle-like leaves off the asparagus fronds, depriving the plants of the ability to photosynthesize
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
and store energy for future years. They also chew the spears and lay generous amounts of eggs on them, making the crop unmarketable. The larvae feed on the plants for a few weeks, then drop to the ground to pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
te. One year may see two or three generations of the beetle. The adults overwinter in a dormant state underground or in nearby leaf litter.
Various insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s are licensed for control, and the parasitic wasp Tetrastichus asparagi Crawford has been successfully used for biological control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
.
The similar spotted asparagus beetle (Crioceris duodecimpunctata) is also a pest as an adult, feeding on tender shoots and leaves, but since the larvae feed only on the asparagus berries it is not considered to be as important.