Young corn plants become infected by the feeding of the flea beetle. Non-infested flea beetles feed on infected plants and then carry the wilt bacterium to healthy plants. As the summer progresses, new broods of flea beetles become infested, greatly increasing the number of contaminated insects. The flea beetles carry and transmit the bacterium as long as they live. The number of flea beetles emerging in spring from hibernation depends on the severity of winter temperatures.
Low temperatures are unfavorable for beetle survival.
The relationship between the winter temperature and disease severity. Above 33 F Severe Flea beetles seldom survive in the northern half of Illinois because of low winter temperatures. Those found in late spring or summer have migrated from the south. Snow or other winter cover apparently has little effect in providing sufficient shelter to enhance survival of the overwintering flea beetles. Prolonged periods of wet summer weather are unfavorable for beetle multiplication and feeding, while dry weather is favorable.