Wireworms

Wireworms are beetle larvae that are found in soil where they feed on roots. They are yellowish brown, thin worms that have a shiny, tough skin. Adults of the wireworms are click beetles, so named because their elongated bodies are capable of producing a clicking sound. Only the larval stage causes damage.

Wireworms feed on roots of emerging plants, killing the seedlings and reducing the stand. As plants mature, wireworms may girdle the stem. Be sure to dig around the plant and look for wireworm larvae to confirm that they are the cause of injury.

In fields known to contain wireworm larvae, fallow during summer with frequent tillage (springtooth or disk). Damage from wireworm infestations to the crop when it is in the seedling stage can sometimes be reduced by replanting. Rotate to nonhost crops if possible; contact your county farm advisor for information regarding nonhosts. Do not plant a susceptible host crop following a crop that has had a heavy infestation of wireworm without fallowing, tilling, or applying a pesticide.

Wireworm infestations are difficult to detect before visible plant injury occurs. They are most likely to be found in a sugarbeet field when sugarbeet follows a long-term legume crop or natural or temporary pasture.

Chemical controls are ineffective or impossible to apply to wireworms attacking a standing crop. If used, chemicals must be applied as preplant or seed treatments.