PHENOLOGY OF AN ESTABLISHED POPULATION OF GALERUCELLA-CALMARIENSIS (L) AND GALERUCELLA-PUSILLA (DUFT) (COLEOPTERA, CHRYSOMELIDAE) ON PURPLELOOSESTRIFE, LYTHRUM-SALICARIA L (LYTHRACEAE), IN SOUTHWEST VIRGINIA

Two beetles Galerucella calmariensis and G. pusilla (Coleoptera: Chrys omelidae) were introduced into Virginia for biological control of purp le loosestrife (Lythrum salicaria). From initial releases of each spec ies made in 1992 in Coeburn, Virginia, the beetles have been recovered for 3 consecutive years and are well established at the release site. Dispersal, as measured by the area covered by the beetles, has been s low; the area with Galerucella spp. increased from 92 m(2) in 1993 to 414 m(2) in 1995, The proportion of purple loosestrife plants with one or more life stages of the beetles increased from 43% in 1993 to 67% in 1995, Both beetle species have one generation per year, Overwinteri ng adults and eggs are found in early May, followed by larvae in late May through mid June, The F-1 adults emerge and feed briefly ill late June and early July before going into diapause. (C) 1997 Academic Pres s.