Adult spotted lanternflies are about 1 inch (2.54 cm) long. At rest they fold their wings over their back like a tent. The wings are grayish with black spots. The antennae appear nearly non-existent because they are very short and bulbous.

The adult wingspan is about 2 inches. The colorful wings are grayish with black spots in front. The hind wings are black, white and deep red. The abdomen is black with yellow stripes.

Spotted lanternflies can cluster on trees in dense groups. Both adults and nymphs may be present.

Spotted lanternfly nymphs change through four stages (instars) before adulthood. The three youngest instars are black with white spots. The fourth instar is black-and-red with white spots. Size ranges from 1/5 to 3/4 inch long as they grow. Fourth instars molt into adults, the only life stage with wings.

Tree-of-heaven (Ailanthus altissima) is a preferred food source. They feed on many other plants too. The photo shows spotted lanternfly nymphs on tree-of-heaven.

Females usually lay egg masses on tree trunks. They may use any other hard or smooth outdoor surface. They cover the egg mass with a grayish, putty-like material. The egg mass is about 1 inch wide by 2 inches long. It is well camouflaged, resembling a smear of mud. Older egg masses reveal 4-7 columns of brownish, seed-like eggs.

Both nymphs and adults feed on plant sap. They excrete the sugary water left after they extract nutrients. This sticky “honeydew” coats surfaces beneath the infested plant. It can cover leaves and fruit, sidewalks, vehicles, chairs and other objects. Honeydew is produced by many sucking insects, including aphids and scale.

The honeydew promotes the growth of unattractive black sooty mold. It stresses the plants by interfering with photosynthesis. It also attracts wasps, bees, and ants. These can cause other problems.