Two sawfly species that feed on white fir were studied in Modoc County, California: Neodiprion near deleoni Ross and N. abietis complex. Neodiprion near deleoni comprised 91 percent of the field Neodiprion populations and spun opaque brown cocoons in the litter or soil. Neodiprion abietis accounted for 9 percent of the field population and spun translucent cocoons that appear green and are attached to foliage. Full-grown larvae, pupae, and adults of the two strains were morophologically distinct, though eggs and young larvae were not. Differences in morphology, phenology, physiology, and behavior are described for the two species.
