Lemony colored eggs are laid in groups of 10 to 100 on the bottom of grape leaves. They hatch in about 7 days. Caterpillars are yellow and tubular. It may have a blue ring near its head and another near its rear. Its 10 yellow bands of color are broken by 11 black hairy rings that can cause painful stings to humans. The spines can cause an allergic reaction that may require medical attention. They have voracious appetites and devour the fleshy green parts of leaves of grapevines causing the plant harm as well as its fruit production. All that remains of the leaf are its veins, still in leaf shape, giving it a skeleton-type appearance. Look for them, with gloved hands and long sleeves, under grape leaves. They chew through them from the bottom. They are a major pest to California grape-growing and wine producing industries. To further aggravate the situation, many generations can be produced in one year making it possible to see a vineyard decimated by the caterpillars in one growing season. They pupate after 40 days of feasting and emerge two weeks later as winged adults, ready and able to reproduce.
A variety of methods are used to control the larvae of the Western Grapeleaf Skeletonizer Moth: introduction of granulosis virus and species-specific parasites, use of insecticide spray, keeping leaf litter and debris away from plant bases, and removing infested leaves.