Seven populations of four species of green lacewings of the genus Chrysoperla were examined for variation at 17 electrophoretically detectable loci. Objectives were (1) to determine the degree of genetic differentiation, if any, that has occurred between two cryptic sibling species, C. plorabunda (Fitch) and C. johnsoni (Henry et al.), which can be distinguished only by differences in their courtship songs and their behavioral reproductive isolation; and (2) to compare those two species with the closely related C. downesi (Smith) and the more distantly related C. harrisii (Fitch). Most of the genetic differentiation in these populations was caused by differences between the cryptic species C. plorabunda and C.johnsoni on the one hand and each of the other two species. Nei's and Roger's genetic distances among all populations were not significantly different. The only significant node was that separating C. harrisii from the other populations. Phenograms from unweighted pair-group method using arithmetic averages (UPGMA) did not resolve the cluster of populations of C. plorabunda and C.johnsoni. These cryptic sibling species are genetically very similar, suggesting recent speciation. Examination of more variable electrophoretic loci, or use of an alternative method such as mtDNA restriction site analysis, might provide enough differences to separate these otherwise good biological species.