Corn rootworm biology & life cycle
Two species of corn rootworm (CRW), Western and Northern, can impact both corn yield and harvestability. Both the larvae and adult stages of corn rootworm result in crop damage. Signs of infested fields include poor root formation, plants with curved stalks (goose necking) or a high proportion of lodged plants.
In the fall, adult CRW look for corn fields on which to feed and lay eggs. These small, white eggs overwinter in the soil and go through diapause (winter chilling) before they hatch. Once the soil temperatures reach 10°C, larvae emerge and feed on corn root hairs for three to four weeks. They also tunnel into the roots resulting in poor water and nutrient uptake, as well as a loss of structural support to the stalk.
Later in the season, adult rootworm feed on fresh corn silks. Severe feeding may affect pollination of sweet corn if the silks are clipped prior to seed set, resulting in a barren cob.
CRW complete only one generation per year.