Grapeleaf skeletonizer

Hodges #

4624

IUCN Red List

not listed

NatureServe

NNR - Unranked

Minnesota

not listed

Grapeleaf skeletonizer is a small, common, and widespread moth. It occurs in the United States east of the Great Plains, in southern Ontario and Quebec Canada, and in Mexico. It is common in the eastern United States. It is less common in the southeast quarter of Minnesota, where it is at the northwestern extent of its range, and is absent from the remainder of the state. Larvae are found in fields and at woodland edges. They feed on the leaves of grape and Virginia creeper, and in other parts of its range also on redbud and peppervine. Adults live only a few days. They are found in fields, where they feed on the nectar of flowers.

Adults are black, are ⅜″ to ⅝″ (10 to 15 mm) in length, and have a 11⁄16″ to 1⅛″ (18 to 28 mm) wingspan. They look similar to yellow-collared scape moth but are smaller.

The head is black. The antennae on both sexes are black and feather-like (pectinate), with branches on just one side of most segments.

The thorax is black. Bright, reddish-orange scales on the first segment of the thorax (prothorax) form a broad collar that extends down the sides. The rear margin of the collar is straight across.

The abdomen is long and black. There is a prominent tuft of hair-like scales at the tip. The abdomen is usually held curled upwards.

The forewings are long, narrow, entirely black, and semi-translucent. The hindwings are much smaller.

The mature caterpillar is stout and up to ⅝″ (1.5 cm) long. The head is partially covered by a fleshy extension of the thorax. The thorax and abdomen are bright yellow. There is a broad black stripe on each side in the subdorsal area, a black band on each abdominal segment, and matching black bands on the thorax. Each black band is armed with tufts of short, shiny, black, stiff hairs (setae). The sides of the abdomen are waxy white. Four long white setae extend forward from the front of the thorax, and four more extend backward from the end of the abdomen. Early instar caterpillars are yellow with just two black spots on each abdominal segment. Middle instars have a band of six black spots on each segment. Final instars have a solid black band on each segment.

Size

Total length: ⅜″ to ⅝″ (10 to 15 mm)

Wingspan: 11⁄16″ to 1⅛″ (18 to 28 mm)

Similar Species

Yellow-collared scape moth (Cisseps fulvicollis) is larger.

Virginia ctenucha (Ctenucha virginica) is much larger. The wings are grayish brown with an iridescent metallic blue base and at least some white in the fringe. There is no tuft at the tip of the abdomen.

Fields and woodland edges

Season

One generation per year in Minnesota: April to October

Behavior

Adults are active both day and night and will come to lights.

Early stage (instar) caterpillars feed side-by-side and tightly spaced, forming a solid mass, always on the underside of leaves. Later instars feed in small groups. Final instar caterpillars are solitary feeders.

The larvae produce hydrogen cyanide, making them poisonous. Their bright coloration is thought to be a warning to potential predators.

Life Cycle

Lemon yellow eggs are lain in a cluster on the underside of a host leaf.

Larva Food/Hosts

Grape (Vitis spp.) and Virginia creeper (Parthenocisis spp.) in Minnesota, and redbud (Cercis spp.) and peppervine (Ampelopsis spp.) elsewhere

Adult Food

Flower nectar