Types of Caterpillars: How to Identify 22 Common Species

North America has close to 11,500 species of butterflies and moths, so there are thousands of types of caterpillars. Luckily you won’t meet most of them. In a US garden the same twenty or so turn up year after year, and two quick checks sort them out: color first, then texture. Smooth, hairy, spiny or horned tells you more than you’d expect, because the handful of species that sting all rely on spines or stiff tufts.

Start with the chart. If your caterpillar isn’t there, identify garden pests from a photo with PlantIn before you touch it.

Caterpillar Identification Chart

Green Caterpillars

Green wins by a mile. A leaf-eater that matches the leaf lives longer, so most garden caterpillars went that way. What separates them is size, stripes, and whether there’s a horn or spines.

Big Green Caterpillars

Anything 7–10 cm long and as thick as a finger is almost always one of four species. On tomatoes, it’s a hornworm (more on those below). On an oak, hickory or walnut, it’s usually a luna or polyphemus moth larva. The luna is bright green with a yellowish line down each side and small pink bumps. A fat green caterpillar nearly 10 cm long with thin white bars is the polyphemus, and it’s the one people most often send photos of. According to the University of Kentucky, neither one stings or harms the tree.

Types of Hornworm Caterpillars: Tomato vs Tobacco

Two hornworms share the tomato patch, and the horn color is the fastest tell. Tomato hornworm: white V marks on the sides, black horn. Tobacco hornworm: diagonal white stripes, red or brown horn. You’ll usually spot the damage before the caterpillar, in the form of stripped stems, bites out of green tomatoes and dark green droppings on the leaves underneath.

The horn looks like a stinger. It isn’t one.

Both spend the winter as pupae in the soil and come back to the same bed. Found one carrying small white cocoons on its back? It has already been parasitized by wasps, so leave it alone, and the wasps that hatch will go after the next hornworm.

Small Green Caterpillars

On cabbage, broccoli or kale, two small green caterpillars do nearly all the damage. The imported cabbageworm is velvety, with a faint yellow line down its back, and eats ragged holes between the big veins. Its partner in crime, the cabbage looper, is paler and has white side lines. Watch it walk. With no legs in the middle of its body, it humps up into a loop with every step. UMN counts up to five generations of cabbageworms a summer, which explains why the holes keep coming back.

Green and Black Caterpillars

Green with black bands and yellow dots, on parsley, dill or fennel: that’s the black swallowtail caterpillar. Poke it and a forked orange “horn” pops out behind its head, along with a strong smell. Texas A&M calls it medically harmless. Plenty of herb growers just plant extra dill for it.

Green Caterpillars With Spikes

Here’s where green stops being safe. Two common green caterpillars sting:

• Io moth caterpillar. Lime green, a red-and-white stripe along each side, and clusters of branched spines. Found on roses, willow, corn and oak. Even its cocoon can sting.
• Saddleback caterpillar. Small (about 2 cm) with a green “blanket” across the middle, a brown oval “saddle” on top, and spiny horns at both ends. Common on maple, hibiscus and crape myrtle in the Southeast.

Black Caterpillars

With a black caterpillar, check the texture before anything else. This group runs from completely harmless to one of the worst stings in the country.

Black Spiky Caterpillars

Two black spiky caterpillars are common enough to know on sight:

• Spiny elm caterpillar. Purplish-black, peppered with white specks, with a row of orange-red spots down the back and branched black spines. Usually in groups on elm, willow or poplar. It becomes the mourning cloak butterfly. UC IPM says the spines can irritate skin, so wear gloves.
• Buck moth caterpillar. Black with tiny white spots and rows of branched spines, on oak in spring. NC State describes the sting as pain that spreads toward the lymph nodes, with redness lasting more than a week.

Black Hairy Caterpillars

Hairy and black is usually good news. Giant leopard moth caterpillars have stiff, glossy black bristles and reach 7.5 cm. Curl one up and thin red rings appear between the segments. It doesn’t sting. Eastern tent caterpillars are hairy too, with a black-and-white stripe down the back and blue spots on the sides, and you’ll know them by the silk tent in a branch fork of a wild cherry or apple in early spring.

A small, mostly black caterpillar crossing a path in October is often a young woolly bear caterpillar. It gains more orange with every molt.

Smooth Black Caterpillars

A smooth, greasy-looking gray-black caterpillar curled into a tight C in the soil is a black cutworm. It works at night and cuts seedlings off at ground level, so the first sign is a row of bean seedlings lying flat in the morning.

Black and Yellow Caterpillars

Most of the time, the black and yellow caterpillar people find is a monarch. It’s banded white, black and yellow, carries two pairs of black filaments (one near the head, one near the tail) and eats only milkweed. Harmless to handle. Predators avoid it because it stores milkweed toxins.

A black caterpillar with yellow stripes on oak, maple or blueberry is more likely the yellow-necked caterpillar. Check behind the head for a bright orange-yellow patch. They feed in groups, and if you disturb them, the whole group lifts heads and tails into a U at once.

Yellow Caterpillars

Give a yellow fuzzy caterpillar a second look before picking it up. American dagger moth caterpillars are covered in soft yellow or white hair, with four long black hair pencils sticking up and a fifth near the rear. You’ll often see one wandering on the ground between July and late October. NC State notes the hairs are reputed to cause a stinging rash.

The white-marked tussock looks almost decorative. Red head, yellow body, four white-to-yellow tufts like little shaving brushes, and a black stripe down the back. Its hairs raise welts within minutes, according to UMass, and the itch can hang around for several days.

Black and Orange Caterpillars

Black at both ends with a rusty orange middle is the banded woolly bear, the caterpillar from the winter-weather folklore, and it’s harmless. The other common black and orange caterpillar is the spiny elm caterpillar from the black section above. That one has orange-red spots and spines, so use gloves.

Brown and Gray Caterpillars

Brown caterpillars are mostly lawn and crop pests, not stingers. Fall armyworms can be brown, green or almost black, so skip the color and check two marks: a white upside-down Y on the face, and four black spots in a square on top of the last segment. Texas A&M warns that armyworms can strip a lawn in a few days, especially after rain.

Hairless, smooth brown caterpillars in a vegetable bed are usually cutworms or armyworms. An evenly rusty-brown, bristly one is probably an older woolly bear.

One brown caterpillar to avoid is the puss caterpillar. It can be tan, brown or nearly white and looks like a small tuft of fur.

White Caterpillars

White and fuzzy usually means a tussock moth. The hickory tussock is white with a row of black tufts along the back and long black hair pencils at each end, and it shows up on hickory, walnut and pecan from July to September. Penn State says its barbed hairs cause a local rash. UMaine adds that the rash can be worse and last longer than with other tussocks.

Hairy Caterpillars: Which Ones Are Non-Poisonous?

Hair by itself isn’t a warning. Woolly bears, giant leopard moths, eastern tent caterpillars and salt marsh caterpillars are all hairy and all safe to handle. Three features mean hands off:

• Long tufts or hair pencils (tussock moths, American dagger).
• Dense fur that hides the body underneath (puss caterpillar).
• Branched spines (io, buck moth, saddleback, spiny elm).

Poisonous Types of Caterpillars

Strictly speaking, these caterpillars are venomous, not poisonous. Their hollow spines or barbed hairs break off in the skin and release toxins. In the US, these are the ones to recognize:

Take the puss caterpillar most seriously. It ranges from New Jersey to Florida and west to Texas, peaking in July and October.

What to Do After a Caterpillar Sting

The National Capital Poison Center recommends:

1. Brush the caterpillar off with a stick or a gloved hand. Never bare fingers.
2. Press tape onto the skin and peel it off. Repeat with fresh tape until nothing more comes off.
3. Wash with soap and water.
4. Ice the area. Ibuprofen or acetaminophen helps the pain, hydrocortisone cream the itch.
5. Call 911 for trouble breathing, fainting, or a swollen face, lips or tongue.
6. See a doctor if blisters form, the rash spreads, or a hair got into an eye.

Moth Caterpillars vs Butterfly Caterpillars

Odds are yours is a moth caterpillar. North America has over 11,000 moth species against roughly 700 butterflies. From the chart, only the monarch, black swallowtail, cabbage white and mourning cloak become butterflies.

Looking at the caterpillar won’t reliably tell you which it’ll become. Wait for the pupa. Butterflies form a bare chrysalis hanging from a stem or leaf, while most moths spin a silk cocoon or pupate in the soil. That’s why turning a tomato bed in spring turns up hard brown hornworm pupae.

How to Identify a Caterpillar

“What kind of caterpillar is this?” usually takes five checks to answer:

1. Color and pattern. Main color, plus any stripes, bands or spots. Find the matching section above.
2. Texture. Smooth, hairy, tufted, spiny or horned. Tufts and spines mean don’t touch.
3. Host plant. Many caterpillars stick to one plant family. A striped one on milkweed is a monarch, and a horned one on tomato is a hornworm.
4. Size. Hold a coin next to it. A hornworm is three to four times longer than a saddleback.
5. Season. Tent caterpillars appear in early spring, puss caterpillars peak in July and October, woolly bears wander in fall.

Worried about the leaves more than the caterpillar? The plant problems guide helps tell caterpillar damage apart from disease.

FAQ

How Many Types of Caterpillars Are There?

There are as many types of caterpillars as there are butterflies and moths. Oklahoma State University counts about 146,000 described species worldwide and nearly 11,500 in North America, most of them moths. In a typical US garden, though, you’ll mostly meet 15 to 25 common ones: hornworms, cabbageworms, armyworms, tent caterpillars, woolly bears and a few others.

What Types of Caterpillars Are Poisonous?

In the US, avoid the puss caterpillar, saddleback, io moth, buck moth, and the hickory and white-marked tussocks. They aren’t poisonous to eat. Their spines or hairs push venom or irritants into the skin. Hornworms, monarchs, swallowtails, woolly bears and giant leopard moth caterpillars are all safe to handle.

Are Green Caterpillars Poisonous?

Mostly no. Hornworms, cabbageworms, loopers, swallowtails, and luna and polyphemus larvae are all harmless. Two green caterpillars do sting: the io moth caterpillar, lime green with a red-and-white side stripe and spine clusters, and the saddleback, which has a green middle and a brown spot. Look for spines, not color.

What Caterpillar Is Eating My Tomato Plants?

Almost always a hornworm. Look for a fat green caterpillar up to 10 cm long with a horn at the rear, plus stripped leaves, chewed green fruit and dark green droppings. Hand-picking is usually enough in a home garden. Leave any hornworm carrying white cocoons, because the wasps inside will go on to attack other hornworms.

Which Caterpillars Turn Into Butterflies?

Among common US caterpillars, the monarch, black swallowtail (parsleyworm), imported cabbageworm (cabbage white) and spiny elm caterpillar (mourning cloak) become butterflies. Hornworms, armyworms, tent caterpillars, tussocks and woolly bears all become moths. A hanging chrysalis means butterfly. A silk cocoon or an underground pupa usually means moth.