Fuzzy White Caterpillar Identification: 7 Kinds

In eastern North America a fuzzy white caterpillar is most often a hickory tussock moth or an American dagger moth caterpillar, both seen from July to October (Wikipedia). The tufts of hair are the fastest way to tell them apart:

• Black tufts down the middle of the back and four long black hair pencils: hickory tussock moth.
• Pale yellow or white hair with a few long black tufts (on two front segments and one near the rear) and a shiny black head: American dagger moth.
• Pale hair with long orange and white hair pencils, on sycamore: sycamore tussock moth.
• Long wispy hairs, dark spots on the back, many caterpillars together in a messy web at the branch tips: fall webworm.
• Evenly fuzzy, no long pencils, colour from white to tan or brown, on low plants: yellow woolly bear.

• Hickory tussock moth (Lophocampa caryae): mostly white tufts with black tufts along the middle of the back and four long black hair pencils; up to 4.5 cm; on hickory, pecan and walnut, also ash, elm, oak and willow; eastern North America (Wikipedia).
• American dagger moth (Acronicta americana): young caterpillars yellow, older ones pale yellow or white, with black tufts on abdominal segments 1, 3 and 8; about 50 mm; on maple, oak, birch, elm and many other trees (Wikipedia).
• Sycamore tussock moth (Halysidota harrisii): yellowish-white hair (A-Z Animals) with two pairs of long orange and two pairs of white hair pencils; 25-35 mm; feeds on American sycamore (Wikipedia).
• Fall webworm (Hyphantria cunea): pale yellow to dark grey with long bristles; up to 35 mm; lives in groups in large, messy webs at the ends of branches, unlike tent caterpillars whose webs sit in branch forks (Wikipedia).
• Yellow woolly bear (Spilosoma virginica): colour varies between individuals, from white or light tan to rusty brown; feeds on low plants including grass and clover (Wikipedia; A-Z Animals).
• White flannel moth caterpillar: 11 pairs of raised yellow tufts; the short needle-like hairs at the base of the tufts sting (University of Kentucky).
• Yellow-tail (UK and Europe): black with long greyish-white hairs, two red lines on top and white blotches; the hairs can be an irritant (Wildlife Trusts).

Often an itchy rash. The hairs of the hickory tussock moth cause contact dermatitis in many people, especially those prone to allergies; Wikipedia cites over 350 documented cases, most of which cleared within 24 hours, with none involving anaphylaxis. American dagger moth hairs are also reported to irritate skin. Some look-alikes, such as flannel moth caterpillars, hide venomous spines under soft hair and can cause severe irritation (University of Kentucky).

If you or a child touched one, the University of Kentucky advises:

• Pull out broken hairs or spines with adhesive or transparent tape.
• Wash the area thoroughly with soap and water.
• An ice pack or baking soda may help reduce pain.
• See a physician if the reaction is severe, and especially for very young, elderly or unwell people.

Get emergency care for trouble breathing, swelling of the face or throat, or hairs in the eye. In the US, Poison Help (1-800-222-1222) can advise on any contact.

Each of them becomes a moth, and several of the moths are pale too:

• Hickory tussock: yellowish-brown forewings with white splotches like stained glass; flies in May and June (Wikipedia).
• American dagger: grey moth with a 50-65 mm wingspan and a sharp double line on the forewing (Wikipedia).
• Sycamore tussock: pale yellow with dark bands on the forewings, about 50 mm across (Wikipedia).
• Fall webworm: mostly white and quite hairy in North America, sometimes with dark spots in the south; 35-42 mm wingspan (Wikipedia).
• Yellow woolly bear: the Virginian tiger moth, white with a darker abdomen (Wikipedia).

Mostly that it is late summer or early autumn. Later-stage hickory tussock and American dagger caterpillars are seen from July to October (Wikipedia), and fall webworm larvae appear in late summer and early fall in the north (Wikipedia). Seeing one is a sign of the season, not an omen; the folk tale about forecasting winter belongs to the black and brown banded woolly bear, not to white caterpillars.

Photograph it where it is, without touching it or letting children pick it up. Take one shot from above to show the tuft pattern and one from the side to show the head and any long hair pencils, and note the plant it was on. InsectLens names caterpillars from photos, including the stinging look-alikes.

Research and drafting for this page used AI assistance. Every figure, date and quotation was then checked line by line against the sources listed at the bottom of the page, each of which was opened while writing. Nothing here is a diagnosis. If a bite, sting or contact with an insect is followed by trouble breathing, swelling of the face or throat, spreading redness, fever or any symptom that worries you, get medical care; in the United States Poison Help (1-800-222-1222) is free and open 24 hours a day.