Diprion pini L is a sawfly whose larvae cause sudden, brief and spectacular defoliation on Pinus sylvestris. In France, bivoltine populations in lowland areas and univoltine populations in mountain areas cohabit, all living in forests located at varying distances from each other. The characteristics of the diapause of mountain populations are different from those of lowland populations. Six natural populations were studied using enzymatic electrophoresis to identify markers reflecting genetic heterogeneity in the French D pini populations: three lowland (Rambouillet, Romorantin, Lorris) and three mountain populations (Saint-Just-Saint-Rambert, Ceillac, Fontchristianne). The study of enzymatic polymorphism concentrated on six loci: three polymorphic esterase loci, a monomorphic malate dehydrogenase locus, a monomorphic and a polymorphic amino-peptidase loci. The determination of genetic distance between populations did not allow us to discriminate between bivoltine lowland populations and univoltine mountain populations. The populations fell into two subgroups: those from the Alps and Rambouillet, and those from central France (Lorris, Romorantin and Saint-Just-Saint-Rambert).