18 Types of Caterpillars in Illinois

Types of Caterpillars in Illinois
Photo by adege on Pixabay

Whether you want to learn about butterflies or moths, there are many fascinating types of caterpillars in Illinois and throughout the United States to observe and learn about!

Some caterpillars are brightly colored, others are camouflaged to blend into their surroundings, and some are even hairy! 

Here are several types of caterpillars that you might see in Illinois.

Some of these caterpillars will later turn into beautiful butterflies, while others may become moths with similar colors or patterns to their larvae phase.

1. American Lady Caterpillar

American Lady Caterpillar - types of caterpillars in colorado
by dogtooth77 is licensed under CC BY-NC-SA 2.0

American Lady caterpillars are the most common and recognizable type of caterpillars in Illinois.

These caterpillars are about four inches long and are yellow with black stripes. They are often seen resting on the ground or a plant during the day, but they come out at night to feed. 

This particular type of caterpillar has two varieties: one that feeds on broadleaf plants and another on coniferous trees.

You can tell which kind it is by looking at its color—yellow for broadleaf plants and green for coniferous trees.

When these critters are done feeding, they will form a cocoon to turn into a moth.

2. Army Cutworm Caterpillar

The Army Cutworm caterpillar can grow to be up to 2 inches long, and they have a dark brown head and tan body with a black stripe down the middle.

They are one of the most commonly seen caterpillars in Illinois. They eat many different types of plants, including soybeans, corn, beans, and pea crops. 

These types of caterpillars in Illinois have a head that turns brown to green and can reach up to 4 inches long.

They are primarily active at night, but during the day, they hide under leaves.

The army cutworm caterpillar eats leaves off your trees and plants. They are also known to be garden pests because they eat vegetables and flowers.

3. Eastern Tent Caterpillar

Eastern Tent Caterpillars - Insects That Start With E
by treegrow is licensed under CC BY 2.0

The Eastern tent caterpillar, Malacosoma americanum, also known as the American Tent caterpillar or the Fall webworm, is a moth found in eastern North America and along the shores of the Great Lakes.

The caterpillar’s distinctive tent spun from silk on a tree branch or shrub can be identified.

It may grow to over four inches long and has an orange head with black spots. 

It feeds mainly on the leaves of apple trees and other fruit trees such as cherry and peach.

When it grows too large for its protective tent, it moves to nearby branches where it spins more tents. The adult moth emerges in July and August.

4. Io Moth Caterpillar

Io Caterpillar
by sarowen is licensed under CC BY-NC-ND 2.0

The Io Moth caterpillars are types of caterpillars in Illinois that can grow up to four inches long and are dark brown with a yellow stripe down the center of their back.

They have blue and yellow spots on their sides. It feeds on plants such as hickory, sumac, cherry, apple, elm, oak, ash, sweetgum, and willow trees. 

The Io Moth caterpillar’s cocoons are usually found on the trunk or limbs of trees, where they wait for their wings to grow so they can fly away.

When touched, it shakes violently from side to side. Some people find this creature fascinating because it moves when touched, and how easy it is to raise them in captivity.

5. Large Tolype Moth Caterpillar

These types of caterpillars in Illinois have yellow-green bodies with dark brown heads.

It has two red lines, which extend from the head to the back end, and some black spots on its body.

Its size ranges from 2 to 3 inches long. This caterpillar feeds on ash, elm, maple, oak, and sycamore trees. 

Some people may see this type of caterpillar as cute, while others find it frightening. Some refer to this type as a puss caterpillar.

Even though they are harmless to humans, they can harm other animals, such as birds, lizards, and small mammals, because they release toxins into their food source.

They do not cause any damage to trees or plants themselves.

6. Giant Leopard Moth Caterpillar

Giant Leopard Moth Caterpillar
by Anita363 is licensed under CC BY-NC 2.0

Smeared dagger moth caterpillars are named for the black-and-white markings on their bodies.

These moths can be found in many parts of North America and have been spotted as far south as Florida. 

The adults are also snake doctors or doctor’s chickens because they resemble a chicken with its wings spread out.

They lay eggs on the leaves and stems of plants, where the larvae hatch and eat their way to the top, where they pupate.

7. Smeared Dagger Moth Caterpillar

Smeared Dagger Moth Caterpillar - Types of Black and Yellow Caterpillars
by Wildreturn is licensed under CC BY 2.0

One of the most common types of caterpillars in Illinois is the Smeared Dagger Moth Caterpillar.

The back and sides are dark brown with a white spot, surrounded by black rings on the top and bottom.

They have long hair on their bodies that looks like bristles, but it’s called setae. This type of caterpillar can be found from April to June.

8. Saddleback Caterpillar

Saddleback Caterpillar
by cotinis is licensed under CC BY-NC-SA 2.0

The Great Tiger Moth caterpillars are some of the most common types of caterpillars in Illinois.

They are also called tussock moths and have long bodies with short hair. Their body can range from light brown to gray with black stripes. 

These caterpillars are usually found on grasses and forbs, feeding on the plants’ leaves.

Caterpillars like the Great Tiger Moth caterpillar have three main stages: egg, larva, and pupa.

The eggs are laid on plants or sticks by female tiger moths looking to reproduce, while the larvae emerge from eggs after about a week or two as small worm-like creatures that continue eating plant leaves.

9. Great Tiger Moth Caterpillar

The Great Tiger Moth caterpillar has a light brown body with black stripes, markings, and yellow bands. It eats leaves from various trees, including birch, elm, and oak.

These types of caterpillars in Illinois can be found from early spring to late fall. 

The larvae are bright green with a red head capsule and black spiracles (the breathing pores on its side).

They feed primarily at night or during the day when it’s raining or cloudy.

You can find this caterpillar in parks, gardens, yards, fields, forests, wetlands, or marshes.

10. Tobacco Hornworm Caterpillar

Tobacco Hornworm Types of Caterpillars in Louisiana
by TexasEagle is licensed under CC BY-NC 2.0

Tobacco Hornworm Caterpillar The tobacco hornworm caterpillar (Manduca sexta) is a moth larva that belongs to the family Sphingidae, and it can be found throughout North America.

Tobacco hornworm caterpillars are known for alternating black and light-colored bands ranging from yellow to pink. 

The tobacco hornworm caterpillar’s black coloration comes from the dark coloration of its digestive system; this coloring also helps camouflage them against the foliage.

They have significant white markings on their sides that resemble spots or stripes and a row of red spots down each side of the abdomen.

These colors serve as warnings to predators that they are distasteful and poisonous.

11. Definite Tussock Moth Caterpillar

The definite tussock moth caterpillar is throughout most of the United States. They are a brownish color with white spots on their sides.

The males also have white antennae and black and yellow spots on their backs, while the females have brown heads. 

These types of caterpillars feed on plants such as oaks, maples, elms, apple trees, and birches.

In the winter, they hibernate in places such as leaf litter or ground debris.

When they are not hibernating, these types of caterpillars like to live on tree trunks, where they spin silk to create their cocoons.

12. Banded Woolly Bear Caterpillar

Banded Woollybear Caterpillar - types of caterpillars in colorado
by Rob Swatski is licensed under CC BY-NC 2.0

The Banded Woolly Bear caterpillars are also known as the Woolly Bear, one of the most common types of caterpillars in Illinois.

They are easily identified because they have a broad white band with alternating black and yellow bands. 

Their bodies are covered with short hairs that make them appear fuzzy, but they’re not fuzzy.

This type of caterpillar has two types: one that overwinters as eggs and another that hibernates as an adult moth. 

The eggs will hatch during the following spring into larvae, which then feed on leaves until they pupate in July or August.

They’ll then turn into moths who will mate, lay eggs, and die within a few weeks. This type of caterpillar can be found throughout North America.

13. Forest Tent Caterpillar

The Forest Tent Caterpillar is one of the most well-known types of caterpillars in Illinois. They are also called the Eastern Tent Caterpillar and the Malacosoma americanum.

These types of caterpillars are hairy, brown, black, and white, with a dark stripe down their back. 

In other words, they look similar to a furry creature that you might find lurking around your basement or backyard.

These types of caterpillars are usually found in forests or woodlands, especially those disturbed by humans, such as logging operations or wildfires.

But don’t worry! If you see these types of caterpillars on your property, they won’t be there for long.

14. Puss Caterpillar

The puss caterpillar, also known as the woolly bear, is a fuzzy brown caterpillar that usually has white stripes on its back.

The name puss derives from the distinctive fur-like coating on this insect’s body.

Puss caterpillars are one of the most well-known types of caterpillars in Illinois due to their abundance and long lifespan. 

They feed on many types of trees and shrubs, including essential food crops such as cherries, apples, and blueberries.

Although it is not typically harmful to humans or other animals, it will occasionally bite if provoked.

15. Luna Moth Caterpillar

The Luna Moth caterpillar is a tiger moth that often lives in gardens. It does not eat plants but instead feeds on aphids found on the underside of leaves.

The caterpillar spends most of its time hiding from predators under leaves or other objects since it has no great defenses.

If you are lucky enough to find one, check out these fun facts: they can be brown or green; they have a yellow band around their body and blue dots near their head.

16. Imperial Moth Caterpillar

The Imperial Moth caterpillar (Eacles imperialis) is a reddish-orange with black-and-white spots and a white stripe running down its back.

These types of caterpillars in Illinois also have yellow bands that run from the top of their head to the bottom of their body.

They measure about three inches long and can be found on deciduous trees throughout the state, especially oak trees. 

The larval stage typically lasts about seven months, but it will overwinter if necessary.

The Imperial Moth caterpillar feeds on leaves from late spring to early fall and pupates in November or December, usually forming cocoons made of silk threads loosely attached to branches or tree trunks.

17. Polyphemus Moth Caterpillar

Polyphemus Moth Caterpillar
by U. S. Fish and Wildlife Service – Northeast Region is licensed under CC PDM 1.0

A type of moth caterpillar, the Polyphemus Moth caterpillar, is bright green and grows about four inches long.

They have a reddish-brown head and an orange-tipped tail, distinguishing them from other types of caterpillars in Illinois.

They are known for the distinctive yellow rings on their body that help scare off predators.

Their diet consists primarily of leaves from various trees, including ash, elm, oak, birch, and hickory.

A Polyphemus Moth caterpillar will typically eat two to three times its weight each day while they’re growing so it can reach its full size within two weeks.

18. Fall Webworm Caterpillar

Fall Webworm
by Benjamin Davidson is licensed under CC BY-NC-SA 2.0

The Fall Webworm caterpillar and the Winter Moth caterpillar are not too different from their name because they produce a cocoon around themselves to protect them during the winter months.

The cocoon for these types of caterpillars in Illinois tends to be smoother and shinier than those produced by other species. 

The Fall Webworm has an average length of 3 cm and ranges in color from light brown to black, with some white or yellow markings on its back.

The body is reasonably pretty rounded, with a few hairs sticking out at various angles.


To conclude, many types of caterpillars in Illinois. Some are more common than others but have unique qualities and characteristics.

If you’re looking to find a new favorite caterpillar this summer and can’t decide which one to choose.

I recommend starting with the following: 

  • The mourning cloak butterfly –
  • The brown winter moth caterpillar
  • The eastern tent caterpillar

Which one do you think will be your new favorite?

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