Control of the frosted scale: Tests in southern California indicate parathion sprays effective treatment against pest on walnut
The frosted scale–Leeanium pruninosum Coq.–is a large, convex black scale about 5/16” long and is covered with a frostlike wax. The eggs are oval and pearly white when first laid, but as they develop under the female scale they turn darker. When ready to hatch they are pale brown in color. The hatch starts early in May and continues into July or–in some areas–into August.