FemaleBlissus leucopterus leucopterus(Say) laid significantly more eggs on sorghum than wheat or corn. More eggs were laid on barley than wheat or corn and less than on sorghum, but numbers were not significantly different. Percentages of eggs hatched and longevity of both sexes on the 4 host plants did not differ. Nymphs developed to the adult stage significantly faster on sorghum than on corn, barley, or wheat, which did not differ significantly from each other. Males developed to the adult stage significantly faster than females but female adults lived significantly longer than males. Last instar nymphs killed seedling sorghum in significantly fewer days than males or females collected from overwintering sites. Overwintering male and female adults with a one week pretest feeding and newly emerged females killed plants in significantly fewer days than newly emerged males or males and females from overwintering sites with no pretest feeding. Chinch bugs collected from the field Sept. 6, Sept. 21, and Oct. 3 and confined to a 16-h photophase actively fed and mated and females laid eggs while those confined to an 8-h photophase did not. This is the first demonstration of a photoperiod induced diapause in this species.