There have been reports of corn flea beetles in southern Iowa from May 4 to 10. Overwintering flea beetles may be infested with the bacterium Pantoea (Erwinia) stewartii, which causes Stewart's disease. Field corn inbreds and sweet corn are particularly susceptible to this disease. Seed producers should pay attention to early season flea beetle populations because, if left unchecked, you could have substantial Stewart's disease during grain fill, resulting in yield loss.