First instars of common green lacewing,Chrysoperla carnea(Stephens), were selected in the laboratory for resistance to carbaryl. After four selections with carbaryl, mortality of larvae decreased from 98% to between 10 and 20% at concentrations well above field rates. Adults of the resistant strain showed significantly greater survival than those of the unselected strain, but still succumbed to rates of carbaryl commonly used in the field. Genetic analyses demonstrated that the resistance does not fit a model of a single completely dominant gene. Tests using the oxidase inhibitor piperonyl butoxide and the esterase inhibitor phenyl saligenin cyclic phosphonate suggest that both oxidase and esterase enzymes contribute to the resistance. No significant cross-resistance to the carbamates propoxur, methomyl, and carbofuran was found. When reared in absence of carbaryl, the carbaryl-resistant strain exhibited lower larval and pupal survival and produced fewer females than the colony from which it was derived. However, its fecundity was significantly higher and adult longevity slightly higher, which compensated in part for reduced survival of immature stages.