- Pest Type: Insect
- Crops Affected: Wheat, Corn, Cereals, Soybeans, Cotton, Peanuts
- Scientific Name: Melanotus spp. or Agroites spp. or Limonius spp.
- Pest Order: Coleoptera
Wireworms go through four stages of growth consisting of egg, larva, pupa and adult; and most wireworm species require two or three years to complete development. Adults emerge in the spring. Shortly after mating, the female beetles lay up to 300 eggs in the soil, generally around the roots of grass plants. Larvae/wireworms emerge from the eggs. Depending on the environmental conditions, the larvae of some wireworms require two to six years to reach full size of approximately 0.8 to 1.5 inches, so numerous stages and sizes of larvae may be found at any one time. The pupal stage is also spent in the soil. Some species of wireworm can overwinter in any of the stages, but most do so in the larval and pupal stages.
Wireworms can attack the crop as soon as the seed is planted into the soil. Injury includes boring into the seed and young seedling plants. Seedlings are usually not completely severed as with cutworm, but suffer severe scaring which weakens the plant. The open wounds also provide paths for other plant diseases. Wireworms/larvae feed on the roots and underground shoots of small grains, especially those planted on land that was previously in sod.
Wireworms are the larval stages of several species of beetles.
Egg: The eggs are generally pearly white, round and difficult to see in the soil.
Larvae: Newly hatched wireworms are white with dark jaws. After feeding and molting several times, these larvae become hard, slender, jointed and shiny; and generally orange, brown or yellow in color. They can be 0.4 to 1.6 inches long, and legs are present on the first three body segments behind the head.
Pupae: Pupae are generally white and soft-bodied.
Adult: Adults of some species are called "click" beetles because of their habit of snapping or clicking when placed on their backs. The adults/beetles are normally 0.06 to 1.5 inches long, are tapered toward both ends, are brown to nearly black and have a loose, flexible joint just ahead of the wings.
Through crop rotation, tillage, soil applied insecticides and seed treatment insecticides, wireworms can usually be managed. Infestations are most severe on land not previously in row crops, especially following sod. Wireworms are difficult to control, partially because they usually live and do their damage several inches deep in the soil. Sometimes baits can be used to determine population levels. If wireworm infestations are high, talk to your local advisers for recommendations in your area.
Wireworm species can be found throughout North America and are damaging to a wide array of crops. Most species tend to prefer heavy, moist soils, especially muck soils. In the U.S., serious wireworm damage to small grains is largely a problem in the northern wheat-growing areas west of the Mississippi River.