Overwintering Bean Leaf Beetles, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae): Density of Populations, Temporal Patterns of Movement, and Survival

The ecology of overwintering bean leaf beetles (BLB), Cerotoma trifurcata (Forster), was studied from June 1981 until May 1983 at four locations in Louisiana to investigate the temporal patterns of movement into and out of overwintering habitats and the density and survival of overwintering populations. Adult BLB entered overwintering quarters from mid-July to early November. All BLB found initially in overwintering sites and thereafter were in diapause. Males entered first, then females. Emergence from overwintering habitats occurred from early March to late May. No BLB were found in overwintering habitats in June or most of July. In the 1981–1982 and 1982–1983 overwintering seasons, the mean peak populations per 2-m2 litter sample were 183 and 33, respectively. Approximately 50% mortality occurred from October to December and survival averaged 18 and 46% in 1981%1982 and 1982%1983, respectively.