Yellownecked Caterpillar

How to identify it

• Full-grown caterpillars are about 2 inches long, black with pale stripes, with a black head and a bright yellow-orange patch behind it.^[1][2]
• The body is covered in long, fine white hairs.^[1]
• When disturbed, the whole group raises both ends of the body.^[1]

Where it lives

NC State calls it one of the most frequently reported pests of oaks, birches and other hardwoods, and Iowa State covers it in Iowa landscapes.^[1][2]

US map: public records from 36 states since 1990 (GBIF). View the map

Biology and life cycle

Moths emerge from the soil in June and July; they are reddish to cinnamon brown with about a 2-inch wingspread.^[1]

Females lay masses of up to 100 or more eggs on the undersides of leaves, and young caterpillars feed in clusters.^[1][2]

In August and September mature caterpillars burrow 2 to 4 inches into the soil to pupate for winter; there is one generation a year.^[1]

Damage and signs

• Hosts include oak, basswood, birch, elm, honeylocust, maple, mountain-ash, walnut and witchhazel, plus blueberry, apple and other fruit trees.^[1]
• Defoliation is usually mild.^[2]

Health risk

NC State and Iowa State treat it as a leaf feeder of trees and note no health concerns.^[1][2]

Control

Traps and physical control

Young caterpillars still in clusters can be removed by pulling off a leaf or pruning a branch tip in mid to late July, or knocked from low branches and crushed.^[1][2]

Biological control

They are parasitized by tachinid flies and eaten by other insects and birds.^[1]

Pesticides

Control is not usually warranted; if it is, spray while caterpillars are small, since late-season control is hard to justify and mature caterpillars are much less susceptible.^[1][2]

Common questions

What are the striped caterpillars in a group on my oak?

In mid to late summer, a cluster of black-and-yellow striped caterpillars with an orange neck patch is likely yellownecked caterpillars.^[1][2]

Do I need to treat yellownecked caterpillars?

Usually not; defoliation is mild. Small, newly planted or stressed trees benefit most from protection.^[2]

Why do they lift their heads and tails?

The whole group raises both ends of the body when disturbed, behavior that may discourage predators.^[1]

Sources

1. NC State Extension, “Yellownecked Caterpillar in the Landscape (PDIC Factsheet).” content.ces.ncsu.edu/yellownecked-caterpillar (accessed 2026-10-15)
2. Iowa State University Extension and Outreach (Yard and Garden), “Yellownecked Caterpillar.” yardandgarden.extension.iastate.edu/encyclopedia/yellownecked-caterpillar (accessed 2026-10-15)
3. iNaturalist, “Datana ministra taxon page (order and family).” www.inaturalist.org/taxa/47719 (accessed 2026-10-06)