Catinathrips kainos O’Neill and Frankliniella vaccinii Morgan overwinter as adults in the soil and first appear on lowbush blueberry plants in mid- to late May. C. kainos was the predominant species on the plants in the spring in six Maine locations. The peak of nymphal abundance occurred in mid-July. It is believed that C. kainos migrates into the soil to complete development while F. vaccinii becomes an adult on the blueberry plant before migrating into the soil. F. vaccinii adults were found to be much more numerous on the plants in late July and August than C. kainos. Although only a few C. kainos males and no F. vaccinii males were noted in the spring, a 3:4 ratio of male to female F. vaccinii adults was present on the plants in August and about the same adult ratio of C. kainos was discovered in the soil in mid-August. The depth at which C. kainos winters in the soil appeared to be centered at 2.5–3.5 in.