These beetles are usually most troublesome after a mild winter followed by a cold spring. Under such conditions, large numbers of beetles survive the winter and attack slowly growing corn over a prolonged period. Growth is retarded and leaves may wilt. Early maturing varieties in the middle Atlantic and southern states are most seriously affected. Life History - Adults generally overwinter in litter and trash around fields.
Mortality tends to be high during harsh winters.
In early spring, beetles move to weeds and then to corn seedlings. Eggs are scattered on soil beneath host plants. In about 10 days, larvae emerge and begin feeding on and tunneling in underground stems, roots, or tubers. They feed for 3 to 4 weeks and develop through 3 instars before pupating in the soil. Seven to 10 days later, a new generation emerges.