'Lygus' reproductive biology and host phenology may be associated with each other and may affect which hosts are invaded, when movement occurs within a season, and which individuals participate in movement. Egg development and size of seminal depository of unmated and mated ' L. elisus' females was characterized for individuals that were colony reared. In colony reared 'L. elisus', egg development occurs independent of mating. Previtellogenic, vitellogenic, then chorionated oocytes are present in 4, 5, and 7 d old unmated and mated females. Mating results in expansion of the seminal depository. Gradually, with time, the seminal depository decreases in size and the number of chorionated oocytes within ovarioles decreases. Multiple mating is suspected to occur in 'L. elisus ' females. 'Lygus elisus' and 'L. borealis' sex ratios, female mating status, and egg development status were determined in individuals collected with a sweep-net from early (seeded May 11) and late (seeded June 14) stands of annual canolaand perennial forage crops in 1994 and 1995. (Abstract shortened by UMI.)