Head capsules of 579 individuals from 28 different populations of gypsy moth,Lymantria dispar(L.), were reliably classified with an analysis of their color spectrum. Based on 26 variables, derived from ≈17 million color combinations of red, green, and blue, a set of numeric characteristics permitted discrimination between gypsy moth populations from the former Soviet Union, the northeastern United States, and the laboratory. Discriminant analysis of color spectra also differentiated among laboratory families reared on the same diet as well as instars within the same family. The 26 variables, which were derived from a series of discriminant analyses and tested on head capsules from populations from Japan, China, Yugoslavia, and Maryland, provided separation as well as a high level of correct classification. This procedure may be useful when head capsule or other spectral data are used in studies of biocontrol, behavior, and population dynamics.