There are several species of sphinx moths that vary somewhat from one another, particularly in color and pattern.
Sphinx moth larvae are distinguished by a long black horn on the back end. When fully grown, the caterpillar is 3 inches long, has a dark button where the horn used to be, may vary in color, and has at least six diagonal white stripes down the sides.
Sphinx moths lay large green eggs singly on the upper surfaces of the outer grape leaves. Eggs hatch after 6 to 9 days. Immediately after hatching, a caterpillar eats a smooth round hole in the leaf and crawls through to the lower surface, where it continues to eat.
Caterpillars feed on grape leaves for about 25 days. They then make their way to the ground and construct a smooth-walled cell in which to overwinter as pupae. First-generation moths emerge during the first half of May. A second brood of moths, much more numerous than the first, appears in early July and the greatest damage is done in August. A generation is completed in about 55 days, and in some years there are three generations.
Sphinx moths are generally minor pests, appearing cyclically. Caterpillars feed on grape leaves, first
causing small round holes and later consuming the entire leaf.
Because the occurrence of sphinx moths is cyclic, noticeable damage is uncommon. Naturally occurring
parasites normally control this pest, and other control should not be needed.