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Wireworms

CROPS IMPACTED: Grass, alfalfa, potatoes, rutabaga and carrots

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Family: Elateridae

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About Wireworms

Reproduction and Life Cycle

Depending on the location and variety of wireworms, their life cycle can take from 2 to 6 years to complete. Adult, larva and pupa wireworms have the ability to overwinter. Female beetles, also known as click beetles, will lay their eggs on the roots of grains and grasses during the spring. These eggs sit at about 2 to 6 inches below the soil line and will hatch 3 to 4 weeks after being laid. For 2 to 5 years the larvae are able to feed and live in the soil before pupating in July or August.

Wireworms Identification and Habitat

Identification

Identifying wireworms is quite easy due to their hard-body and the darkness of their skin in comparison to other grubs and maggots. Adult wireworms are beetles with hard-shells and are dark in colour with a body length of 1 to 3cm long. The eggs that the female adult beetles lay are round and white, which hatch hard-shelled larvae that are about ½ to 1 inch long. Wireworm larvae are typically copper to tan in colour with an elongated last abdomen body segment and 3 pairs of legs.

Habitat

Wireworm infestations are most common in fields that are alfalfa and grass-based pastures that are infested with grassy, broadleaf weeds. If a field is only planted with alfalfa, increased infestation should not happen. Some vegetable crops such as potatoes, rutabaga and carrots (especially in wet soil) have high infestations. If wireworms infested fields with larger seed, they may be hollowed out or if plants have started to grow, they will be killed soon after emergence from the wireworms feeding. As the temperature and moisture in the soil changes, wireworms will move up and down in the soil. Throughout the spring, also known as the growing season, wireworms come to the top inches of the soil when its temperature is about 10 to 26˚C. If the soil temperature gets to be higher than 26˚C and becomes quite dry, wireworms will borrow to 24 inches below the surface of the soil.

Wireworms Management and Control Methods

Cultural Control

It is important to know the history of your crop fields; this will help you avoid planting grasses into your plant rotation. Due to the fact that there is a wide variety of host plants for wireworms, crop rotation is only somewhat helpful. Throughout the growing season it is also suggested to remove all grassy weeds from crop fields

Chemical Control

Once crops have been planted, there is no insecticide that is able to provide control over wireworms. If you are looking for control in tomato crops, Orthene (acephate) is a transplant water treatment that works well. For control on sugar beets and sweet corn, counter 15G (or terbugos) can be used at planting time to provide control. The fumigant Vorlex Plus can work to control wireworms in most vegetable crops. However, widespread soil fumigation at times is not a good economic management or sustainable control method.

Latin / Alternative Wireworms Names

  • - Elateridae
  • - Click beetles
  • - Kipjack
  • - Snapping beetle
  • - Spring beetle

Sources

http://www.omafra.gov.on.ca/english/crops/facts/00-047.htm

http://www.britannica.com/animal/click-beetle

http://mint.ippc.orst.edu/wirewcycle.htm