If you’ve spotted a black and white caterpillar, you’re most likely looking at a hickory tussock moth caterpillar, a white-marked tussock moth caterpillar, or one of several other common species that share this striking color pattern. The good news is that most black and white caterpillars are not dangerously venomous, but some can cause a painful skin rash if you handle them. Identification matters because it tells you whether to admire from a distance or take steps to protect your garden.
Hickory Tussock Moth Caterpillar
This is one of the most commonly encountered black and white caterpillars in eastern North America, and it’s the one that generates the most worried phone calls to extension offices every fall. The hickory tussock moth caterpillar is covered in dense white hairs with a distinct row of black tufts running down the center of its back. It also has longer black hair “pencils” extending from either end of its body. You’ll find them on hardwood trees like hickory, walnut, ash, and oak from late summer through early fall, often in large groups on branches before they disperse to pupate.
Despite its fuzzy, almost friendly appearance, this caterpillar is one you should not pick up. Its white and black hairs are barbed and easily detach, embedding in your skin, eyes, or mucous membranes. Contact typically causes a localized rash with itching. It’s not a medical emergency for most people, but it’s uncomfortable enough that you’ll want to avoid a repeat experience. Children and pets are especially likely to grab them out of curiosity.
White-Marked Tussock Moth Caterpillar
This caterpillar is one of the more visually dramatic species you’ll encounter. It grows to about 1 to 1.5 inches long and features a combination of colors that makes it easy to identify: two forward-pointing black hair pencils that extend beyond the head, a single rear pencil of black hairs at the tail, and four dense white clumps of short bristles sitting like tiny toothbrush heads on top of its back. Adding to the display, it has two bright red bumps near the rear of its body and a red or orange head.
White-marked tussock moth caterpillars feed on a wide range of deciduous and evergreen trees and can occasionally defoliate ornamental plantings. Like the hickory tussock, some of their hairs contain irritating material that can cause skin reactions in sensitive people. The caterpillars hatch in spring and feed for several weeks before pupating. You’ll sometimes find their fuzzy white egg masses attached to the sides of buildings, fences, and tree bark over the winter.
Zebra Swallowtail Caterpillar
Not all black and white caterpillars are fuzzy. The zebra swallowtail caterpillar is smooth-bodied and changes appearance dramatically as it grows. Early-stage larvae are dull gray, but middle-stage larvae develop distinct black, yellow, and white transverse bands. In their final stage before pupating, they turn green with blue, black, and yellow bands, though some remain dark-colored throughout. These caterpillars feed exclusively on pawpaw trees. If you find a banded caterpillar on a pawpaw leaf, you’re almost certainly looking at this species.
Unlike the tussock moths, zebra swallowtail caterpillars have no stinging hairs and are completely harmless to handle. They do have a small forked organ behind the head called an osmeterium that they can extend when threatened, releasing a mild odor to deter predators. It’s startling but not harmful. These caterpillars grow into one of the more elegant butterflies in North America, with long-tailed black and white striped wings.
Other Black and White Species
Several other caterpillar species display black and white patterns. Woolly bear caterpillars (the larvae of Isabella tiger moths) are typically banded in black and reddish-brown, but some individuals appear very dark with pale bands that can read as black and white. Fall webworm caterpillars create conspicuous silk tents on tree branches and can be pale with dark spots. The catalpa sphinx caterpillar is a large, striking species with bold black and yellow-white markings found on catalpa trees.
Cross-striped cabbage worms are a garden pest worth knowing about. These smaller caterpillars have alternating black and white (or grayish) horizontal bands and feed on broccoli, cabbage, kale, and other plants in the mustard family. If you find black and white caterpillars on your vegetable plants, this is a likely culprit.
Are They Dangerous to Touch?
The general rule is simple: if it’s fuzzy, don’t touch it. Hairy or spiny caterpillars use their bristles for defense. The barbed hairs of tussock moth caterpillars detach easily on contact and embed in your skin, causing itching and a rash that can last several days. Some people develop more significant allergic reactions. Smooth-bodied caterpillars, by contrast, are almost always safe to pick up gently.
If you do get stung by a hairy caterpillar, resist the urge to rub the area. Press a strip of tape (any kind) firmly onto the affected skin and peel it off to pull out the embedded hairs. You may need to repeat this several times. Then wash the area with soap and water. If the hairs haven’t embedded and are just sitting on the surface, soap and water alone will take care of it. Over-the-counter anti-itch cream can help with the rash that follows.
Managing Caterpillars in Your Garden
If black and white caterpillars are chewing through your plants, your approach depends on the scale of the problem. A few caterpillars on a healthy tree or shrub rarely cause lasting damage, and hand-picking them (with gloves, for hairy species) is the simplest solution. Drop them into a bucket of soapy water.
For larger infestations, a biological spray containing a naturally occurring soil bacterium is the most targeted option. It’s sold at most garden centers and affects only caterpillars that eat treated foliage, leaving beneficial insects unharmed. It works best on young, actively feeding caterpillars and needs to be reapplied after rain or heavy sun exposure, since ultraviolet light breaks it down. Thorough coverage on both sides of leaves is important because the caterpillars have to actually consume it for the treatment to work. On plants with waxy leaves, adding a spreader-sticker product helps the spray adhere.
Preventive steps go a long way too. Clearing plant debris in fall removes overwintering pupae, and keeping weedy borders trimmed eliminates alternate host plants that attract egg-laying moths to your garden in the first place. For high-value crops, tiny parasitic wasps called Trichogramma are commercially available. These wasps lay their eggs inside caterpillar eggs before they hatch, completing their own life cycle in about 7 to 10 days. Timing matters: they only work against the egg stage, so you need to release them when moths are actively laying. Protect them from ants, which will prey on the wasps.
How to Identify What You’ve Found
When trying to match a caterpillar to a species, note these details: the overall body shape (fuzzy or smooth), the specific pattern of markings (stripes, bands, spots, or tufts), the plant it’s feeding on, and your geographic location. Host plant is one of the strongest clues. A fuzzy black and white caterpillar on a hickory or walnut tree is almost certainly a hickory tussock. A smooth banded caterpillar on pawpaw is a zebra swallowtail. A striped caterpillar on your cabbage is a cross-striped cabbage worm.
Your state’s cooperative extension service offers free identification help, often by email with a photo. This is worth doing if you’re seeing large numbers or if the caterpillar is on a plant you care about, since management depends on knowing exactly which species you’re dealing with.