LIFE-HISTORY AND HOST-SPECIFICITY OF APHTHONA-VENUSTULA KUTSCH (COL, CHRYSOMELIDAE), A CANDIDATE FOR THE BIOLOGICAL-CONTROL OF LEAFY SPURGE(EUPHORBIA-ESULA L) IN NORTH-AMERICA

Studies on the life history and host specificity of the root-feeding c hrysomelid Aphthona venustula were made to determine the suitability o f this insect as a classical biological control agent for leafy spurge (Euphorbia esula) in North America. The adults of A. venustula emerge in summer, and are in reproductive diapause until the following sprin g when the main adult feeding and oviposition activity occurs. A. venu stula prefers mesic shaded and transitional areas but can survive on f ormerly forested land. The experimental adult feeding range of the bee tle is restricted to species in genus Euphorbia, while the larval feed ing range is restricted to species in subgenus Esula. Within its habit at in Europe, the beetle discriminates between species in subgenus Esu la.