does not appear. First page follows. History of the Problem The group of hemipterous insects belonging to the genus Lygus, of the family Miridae, has long been recognized as injurious to many agricultural crops and ornamental plants. In the past fifteen years two species of this genus—L. hesperus Knight and L. elisus Van Duzee—have been shown to cause flower drop and injury to pods and seeds of beans (Shull, 1933);4 flower drop and shriveled seed in alfalfa (Sorenson, 1936), (1939); (Shull, Rice, and Cline, 1934) and sugar beets (Hills, 1941); (Hills, 1943); and shedding of the squares and other injury to cotton. (McGregor, 1927); (Ewing, 1929); (Cassidy and Barber, 1939). As a result of these findings much information has been accumulated on the biology of these insects in relation to each of these host crops (Shull, 1933); (Sorenson, 1939); and (Smith, 1942). The relation of lygus bugs to flower drop and shriveled seed of alfalfa has been the subject of extensive investigations by (Sorenson (1932), (1939), (Shull, Rice, and Cline (1934)), (Carlson (1940)), and (Stitt (1940)), in which they have shown the importance of these insects in limiting alfalfa seed production. (Shull, Rice, and Cline (1934)) were the first to suggest that lygus bugs might be a factor in alfalfa hay production. In their experiments, they put cages over four areas, each of which had from 17 to 20 plants. Two of these plots served as checks; on the others a population of bugs was maintained. An average of 17.5 per cent less hay was produced in the infested than in the check cages. (Sorenson (1939)) confined lygus bugs on alfalfa plants, and measured the lengths of the stems at various intervals. He found 8 to 35 per cent reduction in the length of the stems as a result of injuries caused by the bugs.
