Fall Diapause, Winter Mortality and Spring Emergence of the Tobacco Budworm 1 in the Delta of Mississippi 2

Late 5th-instar larvae of the tobacco budworm, Heliothis virescens (F.), collected in the field, primarily in cotton and soybeans, at Stoneville, MS in the fall of 1976 and 1977 and held in field cages produced diapausing pupae that survived the winter. Of 837 and 490 larvae caged in these years, 3.6 and 3.9%, respectively, emerged as adults in the following year. In 1977 and 1978, the period and pattern of adult emergence from the overwintered pupae indicated that adult emergence is controlled primarily by soil temperature during late winter and spring and that day length during this period has little if any influence. Low temperatures and excessive rainfall during the normal emergence period may delay emergence of some individual insects.