Lepidoptera: Noctuidae: Ascalapha odorata ( Linnaeus, 1758) (Black Witch)

Because of its great size ( a wing span of 6 to 7 in., or 15 to 18 cm), this moth might be mistaken for a member of the giant silk moth family, or even a bat. However, it is merely a giant cutworm or owlet moth.

Its caterpillar will not be found in the basin, although the moth occasionally appears around lights in the late summer or fall (August to October).

Both sexes have dark brown wings marked with transverse dark and light squiggly lines. There is a small round clear area midway along the leading edge of the fore wing and a partial eye-like spot at the apex of the hind wing. Females are much lighter in color than males and give off a violet reflection when rotated under a light.

Photograph by C. Hogue

The species is probably not a permanent resident of the continental United States, although it may persist for several successive generations in the Los Angeles area on ornamental acacias. The Black Witch is actually a tropical insect and is very common in Mexico, Central America, and northern South America. It habitually migrates northward, however, when warm humid weather prevails. Specimens (mostly males) have been taken, usually in a worn condition, in the extreme northern states and Canada. At home in the tropics, the caterpillars feed on acacias and cassias. They are nocturnally active, resting during the day on the bark or branches of the host tree.

The mature larva is large (almost 2 1/2 in., or 63 mm long), plump, and cylindrical although slightly wider at the fourth segment. There are broad black broken stripes on the sides of its back and a very incomplete dark band running along its sides through the large black spiracles.

© 1993 Insects of the Los Angeles Basin