19 Types of Caterpillars in Iowa

Types of Caterpillars in Iowa
Photo by adege

How many types of caterpillars are there in Iowa? There’s more than you may think.

Many people only think of the giant swallowtail butterfly when they consider the world of caterpillars in Iowa, but there are plenty more to be discovered and appreciated. 

Learn more about these unique creatures and why they’re so crucial to the ecosystem in this list of types of caterpillars in Iowa you’ve probably never heard of!

1. Monarch Caterpillar

The monarch caterpillars, DANAUS PAULINA, are types of caterpillars in Iowa and are species of butterfly (Danaus Paulina) native to North America. It can be found throughout most of Mexico and up into southern Canada (excluding Labrador). 

The monarch may reach a wingspan over six inches long and has been recorded living for up to ten months. All that time is spent as a caterpillar.

By October, it will begin migrating south through Texas and then across Mexico, where it will return in March.

2. Cabbageworm

What does it look like? Often mistaken for a leaf, these types of caterpillars in Iowa have caused damage to cabbage and broccoli.

They usually arrive on plants early in spring. The best way to prevent an infestation is by keeping watch over your garden so you can identify them. 

Once spotted, pick them off and dispose of them immediately by crushing or dropping them into soapy water – do not release them back into your garden.

If left alone, cabbage worms will eat their way through your garden until all left is yellowed leaves and stems. 

The Imported Cabbage Worm: This bright green pest has yellow stripes along its sides; it is easily identified due to its small size and oval shape.

3. Woolly Bear

It is pretty easy to differentiate between butterflies and moths. Butterflies have thin antennae, while moths have thicker ones. Moths also do not fly at night because they are not strong fliers like most butterflies. 

Finally, another way to differentiate between butterflies and moths is that a butterfly’s wings are more brightly colored on top than underneath. In contrast, moth wings are usually darker on top and lighter underneath. 

One type of caterpillar you may not know about is a woolly bear. These types of caterpillars in Iowa are brown or black with white or yellow stripes running down their sides. They can grow up to 3 inches long!

4. Viceroy Caterpillar

Don’t be fooled by these cute, green-and-yellow types of caterpillars in Iowa that mimic monarchsManyny people mistake them for monarchs because they’re so similar. However, rulers don’t just look like monarchs—they act like them too. 

In other words, if you see a colony of viceroys on your tomato plants or other garden plants, it’s already too late, and there’s nothing you can do to save your crops.

So beware, next time you spot a cluster of green-and-yellow caterpillars hanging out on your plants, leave them be! 

The only good thing about the viceroy caterpillar is their larval stage—when they live off ants by laying their eggs on ant nests.

5. Large Maple Spanworm

The Large Maple Spanworm (Dryocampa rubicunda) is a moth species belonging to Psychidae. It’s not common, but it was recently spotted in Des Moines, Iowa!

Their wingspan can be up to 5 cm (2 inches), making them one of the giant caterpillars native to North America. 

If that’s not enough for you, keep reading for more fascinating facts about these caterpillars. In contrast to other types of caterpillars in Iowa, Large Maple Spanworms are large and black with yellow stripes.

They have long antennae and large eyespots on their hindwings, which defend them when predators threaten them.

6. Variegated Fritillary Caterpillar

This caterpillar is what most people think of when they think of types of caterpillars in Iowa. Bright yellow and black strips, red eyespots—it’s pretty easy to spot.

Adults look similar to butterflies, with a wingspan that ranges from 1 3⁄4 inches to 4 1⁄2 inches. 

The variegated fritillary can be found throughout much of North America and has orange spots on each wing that can vary significantly in size and color between individuals.

You probably wouldn’t notice the smallest known insect in Iowa if you weren’t looking for it. These tiny creatures are so small that even as adults, their bodies are about half an inch long.

7. Curve-Lined Owlet Moth Caterpillar

First up is another pretty one. The curve-lined owlet moth caterpillar is an inch long when fully grown and has a black head with two white stripes. It likes to eat cherry, plum, apple, and peach trees. 

In Iowa, that’s not a problem since we don’t grow those, but in other parts of North America, it causes severe damage to their crops.

There’s no point getting mad at them for eating your apples; they’re just trying to make a living like everyone else. After all, what would you do if you couldn’t eat for several weeks?

8. Tobacco Hornworm

The tobacco hornworm is relatively standard, but it’s often mistaken for another species—the tomato hornworm.

Both are green types of caterpillars in Iowa with black dots on their skin and a reddish-orange stripe down their backs.

The tomato hornworm can be distinguished by its four white horns along its back, while tobacco caterpillar larvae have only two rows of black dots with one at each end. 

Otherwise, they’re identical. Many lists suggest that we consider them a single species; it’s easier to consider them a single species.

Tobacco hornworms eat tomatoes, sometimes tobacco leaves, and occasionally other plants. Adults can fly and move long distances during mating season.

9. White-Marked Tussock Caterpillar

The Eastern Tiger Swallowtail is a large butterfly that ranges throughout the United States. While its distinctive black and yellow stripes often recognize, you might be surprised to learn that these unique colors are only visible to birds. 

The Tiger Swallowtail caterpillar camouflages itself with an appearance that makes it resemble bird poop.

Although easily avoided by predators, birds will still chow down on these types of caterpillars in Iowa if they get a chance—sometimes even eating them before they have time to develop into adult butterflies.

10. Milkweed Tussock Caterpillar

The milkweed tussock caterpillar, also known as the hairy caterpillar or woolly worm, is a type of caterpillar commonly found in Iowa.

Unlike most types of caterpillars in Iowa, it looks like a round ball with spikes sticking out from its body. These spikes can cause skin irritation if they come into contact with your skin and are best left alone. 

The caterpillar can be found on milkweed plants from June to early October before forming a cocoon and emerging as an adult moth.

If you find one of these types of caterpillars in Iowa outside, you can pick it up by holding onto its tail end rather than its head. 

If you get stung by one of these creatures, place a cold pack on the area where you were stung for 10 minutes.

Repeat three times daily until symptoms disappear; then apply calamine lotion and take an antihistamine to reduce itching. Contact poison control if symptoms persist more than 48 hours after initial treatment.

11. Banded Tussock Caterpillar

Unlike most caterpillars, Banded Tussock Caterpillars are social creatures. When they’re young, they live as a group to enjoy increased protection from predators. Banded Tussocks can be found alone as they mature and become more independent. 

This species is also one of the few that releases pheromones to attract a mate. They have reddish hairs on their body with a yellow stripe running down their backs.

The streak is often broken or narrow, leading some scientists to believe that it only serves as a visual marker when two types of caterpillars in Iowa are paired up to defend themselves against attackers rather than attract a mate.

12. Giant Leopard Moth Caterpillar

This bright yellow caterpillar can reach five inches long and has black spots with orange legs and a pair of eyes on its side.

Giant leopard moths are found all over North America but are less common than other types of caterpillars in Iowa.

When it’s time to turn into a moth, these have patterns that look like a leopard’s fur, which is where they get their name. 

Their bodies are as wide as three inches and covered with bristly spines. They tend to hang out at night near porch lights because their eyes reflect light; during the day, they like to hide under leaves or debris.

13. Parsley Caterpillar

Whether or not you have a green thumb, one thing’s for sure–Iowa has an abundance of caterpillars just waiting to be cataloged.

So much so that it’s nearly impossible to count them all. There are more than 300 types of caterpillars in Iowa inhabiting our great state! 

To celebrate their existence, here are some caterpillar facts you might not know: Although they only take up a small amount of space compared to butterflies and moths, caterpillars can be surprisingly massive when put on a scale–the monarch butterfly larva is commonly known as the size of your thumb! 

Don’t expect it to stay that way by adulthood; they’ll weigh less than half an ounce. Still heavy enough to carry around, though!

14. Eastern Tiger Swallowtail Caterpillar

This butterfly caterpillar has a row of black and white spots along its back and is found across Iowa. It’s big and bold, making it easy to spot just about any type of plant.

These types of caterpillars in Iowa will eventually transform into a black-and-yellow Eastern Tiger Swallowtail Butterfly, which looks like two eyes staring at you from above. 

This butterfly might only be able to travel a couple of hundred feet during its lifetime, but that’s all it needs to find food for itself and the eggs it lays on twigs or leaves so that its babies can hatch when they’re ready.

15. Spicebush Swallowtail Caterpillar

Spicebush Swallowtail caterpillars are bright green with yellow stripes and come from a type of sassafras tree. They’re beautiful, but you won’t want to handle them; they’re toxic! 

Spicebush Swallowtail caterpillars eat leaves from sassafras trees, so if you see them (and can identify what kind of tree they’re munching on), that’s how you’ll know which trees to leave alone.

Do not – I repeat, DO NOT – touch one of these types of caterpillars in Iowa; their toxicity may cause hallucinations and even diarrhea if ingested.

16. Cecropia Moth Caterpillar

Though these green caterpillars aren’t quite as pretty as butterflies, they’re just as important to ecosystems.

The Cecropia moth is a polyphagous species, meaning it feeds on multiple plants rather than one particular type of food.

It’s a voracious feeder and can completely defoliate trees like oak, hickory, maple, and birch – but it doesn’t kill them. 

Its population is controlled by parasites, natural predators, and diseases that keep it from feeding too much.

In some areas around South America, if Cecropia moths are found early during their population explosion cycle when they’re abundant but still small (less than about an inch), people trap them for consumption!

17. Monkey Slug

This caterpillar is covered with soft hair that makes it look like a slug. Like other types of caterpillars in Iowa, it eats leaves, and its strands are thought to make it difficult for predators to handle. It is a little over an inch long when fully grown and can be yellow, brown, or black. 

The larvae can sometimes be found feeding on stinging nettle plants (Urtica dioica). They are prevalent throughout Iowa, but they prefer oak trees.

Its favorite plant is wild raspberry (Rubus strigosus); however, if you see some unusual damage on your raspberries and live within range of monkey slugs (in Iowas), keep an eye out for them!

18. Spotted Apatelodes Caterpillar

These types of caterpillars in Iowa are most easily identified by two yellow spots on each side of their body and a ring-like yellow pattern on their back.

Although a few other species resemble it, you’ll only find Spotted Apatelodes caterpillars on oak trees. I found these guys feeding on pin oaks in Central Park. 

They tend to hang out alone or with their siblings; try not to get too close when you’re checking them out because they might be munching! The spotted apatelodes caterpillar will become a beautiful black swallowtail butterfly.

19. Io Caterpillar

The Io Moth caterpillar (Automeris io) is a resident of Iowa. It feeds on deciduous and evergreen trees and shrubs and can cause considerable defoliation to its host plants.

However, they are rarely seen because they spend much of their lives hanging from branches or crawling through low vegetation. 

Look for their distinctive greenish-brown body with pale stripes extending down their sides and tiny white tufts on each segment near where they connect to their legs. The Io Moth caterpillar grows up to 4 inches long.


Today, you read about four types of caterpillars in Iowa you’ve probably never heard of. Still, even though these species aren’t widespread, they’re fascinating. 

You should join a local moth society. It’s an excellent way to meet other naturalists who love moths! If not, there’s always Google!

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