20 Caterpillars in Iowa with Pictures and Identification

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Caterpillars are incredibly captivating creatures, undergoing a remarkable transformation into butterflies or moths. Iowa is home to a vast array of caterpillar species, although this article focuses on 20 of the most intriguing and prevalent ones for your exploration.

The 20 most common Caterpillars in Iowa

1. Io Caterpillar

In Iowa, deciduous and evergreen trees are the main food source for Io Moth caterpillars (Automeris io), which causes extensive defoliation. They are elusive and frequently seen balancing on branches or moving through low vegetation. They can be identified by their pale stripes and greenish-brown body, together with little white tufts near their legs. They can extend up to 4 inches in length.

2. Spotted Apatelodes Caterpillar

The dual yellow spots on each side and the yellow design like a ring on the back of the Spotted Apatelodes caterpillar in Iowa are characteristics that identify it. They are unique to oak trees, frequently seen in pairs or alone, and are typically observed in Central Park nibbling on pin oaks. Watch them carefully since they may be eating. These caterpillars eventually mature into magnificent black swallowtail butterflies.

3. Monkey Slug

Because of its delicate, hair-like covering, the caterpillar of the Monkey Slug in Iowa looks like a slug. It is about an inch long, with yellow, brown, or black varieties, and is well-known for its protecting strands and leaf-eating activities. In addition to stinging nettle (Urtica dioica), which they frequently see on oak trees, these caterpillars also like wild raspberry (Rubus strigosus). In Iowa, be aware of these caterpillars if you observe any odd damage to your raspberries.

4. Cecropia Moth Caterpillar

Ecosystems depend heavily on the green caterpillar of the Cecropia moth, despite its lack of beauty compared to butterflies. It eats a wide variety of plants, including birch, oak, hickory, and maple, and because it is polyphagous, it causes significant defoliation without endangering the trees. Diseases, parasites, and natural predators all aid in population control. In certain regions of South America, during the initial phase of their population boom, individuals catch and eat these caterpillars at the size of less than an inch.

5. Spicebush Swallowtail Caterpillar

The sassafras tree is the source of the beautiful yellow-striped Spicebush Swallowtail caterpillar, which has a vivid green body. But use caution—handling them can be harmful. Recognized by their consumption of sassafras leaves, these caterpillars indicate which trees are dangerous to approach. In Iowa, it is imperative that you avoid handling them because they are hazardous and if ingested, can cause hallucinations and stomach problems.

6. Eastern Tiger Swallowtail Caterpillar

In Iowa, the caterpillar known as the Eastern Tiger Swallowtail is widely distributed and has a line of black and white markings on it. It is immediately noticeable on a variety of plants because to its big size and unique form. This caterpillar eventually transforms into the eye-like patterns on its wings, identifying it as the distinctive black-and-yellow Eastern Tiger Swallowtail Butterfly. Even though it can’t move very far, it can find food and good places to lay eggs within a few hundred feet, which helps to guarantee that its young survive.

7. Parsley Caterpillar

A paradise for caterpillar fans, Iowa is alive with a wide variety of caterpillars. These caterpillars, which have over 300 different species, are diverse in size and shape, with some being unexpectedly huge when measured. The caterpillar of a monarch butterfly, for example, weighs less than half an ounce when it matures from being the size of a thumb. They’ve lost weight, yet they’re still heavy enough to carry.

8. Giant Leopard Moth Caterpillar

With its eye-catching yellow color, black spots, and orange legs, the huge larva of the Giant Leopard Moth can reach a length of five inches. Although they can be found all over North America, in comparison to other caterpillar species, they are comparatively less abundant in Iowa. Their name comes from the large patterns on their fur that resemble leopards and become noticeable when they turn into moths. These caterpillars are covered with bristle spines and can have bodies up to three inches broad. They are nocturnal animals that prefer to hide under leaves or other debris during the day. Because of their light-reflecting eyes, they are frequently spotted next to porch lights.

9. Banded Tussock Caterpillar

Banded Tussock Caterpillar are unique in that they exhibit social interaction in their early life, which increases their defense against predators. They usually start living on their own when they get older. These caterpillars have a yellow stripe running down their backs and reddish hairs. They use pheromones to mate. In Iowa, some experts propose that the stripe serves more as a defense strategy for paired caterpillars than it does as a means of luring mates.

10. Milkweed Tussock Caterpillar

Milkweed Tussock Caterpillar, often known as the woolly or hairy worm, is a unique insect that is frequently seen in Iowa. It is advisable not to touch the spiky protrusions covering its spherical shape, since they may cause skin irritation. Before turning into adult moths, they usually live on milkweed plants from June until the beginning of October. It’s safer to handle one by the tail end rather than the head if you come across one outside. Use a cold compress on a sting for ten minutes, three times a day, or until the pain goes away. Itching can be reduced with calamine lotion and antihistamines; if symptoms don’t go away after 48 hours, call poison control.

11. Eastern Tiger Swallowtail

The Eastern Tiger Swallowtail, a sizable butterfly found across the US, boasts recognizable black and yellow stripes that are primarily discernible to birds. In contrast, the Tiger Swallowtail caterpillar cleverly mimics bird droppings, effectively evading most predators. However, birds occasionally consume these caterpillars in Iowa before they have a chance to mature into adult butterflies.

12. Tobacco Hornworm

Common in Iowa, the Tobacco Hornworm is a green caterpillar with black dots and a reddish-orange stripe down its back. It is sometimes confused with the tomato hornworm. The tobacco caterpillar has two rows of black spots, one at each end, whereas the tomato hornworm is distinguished by its four white horns down its back. Because of their similarity, some regard them as a single species despite their differences. These caterpillars consume several plants, including tomatoes and occasionally tobacco leaves. Adult hornworms are able to fly and cover great distances when mating.Tobacco hornworms eat tomatoes, sometimes tobacco leaves, and occasionally other plants. Adults can fly and move long distances during mating season.

13. Curve-Lined Owlet Moth Caterpillar

An inch in length, the Curve-Lined Owlet Moth caterpillar has a black head with two white stripes. Its preferred food consists of apple, peach, plum, and cherry trees; in other parts of North America, this causes significant crop damage. Although this isn’t a problem in Iowa, it’s important to realize that, like everyone else, these caterpillars are just trying to survive. Ultimately, how would you handle a few weeks without food?

14. Variegated Fritillary Caterpillar

In Iowa, the Variegated Fritillary Caterpillar is easily identified by its striking black and yellow stripes and its characteristic red eyespots. Adult fritillaries have wingspan ranging from 1 3⁄4 inches to 4 1⁄2 inches, resembling butterflies. They are widespread in North America and have distinct, variably colored and sized orange spots on each wing. However, if you’re not actively looking for it, the smallest known bug in Iowa—which has a body length of only about half an inch even as an adult—may go unnoticed.

15. Large Maple Spanworm

Despite being uncommon, the Large Maple Spanworm (Dryocampa rubicunda), a member of the Psychidae family, was recently observed near Des Moines, Iowa. Reaching up to 5 cm (2 inches) in wingspan, it is one of the biggest native caterpillars found in North America. These large black caterpillars with yellow stripes on them are very identifiable. They use their long antennae and noticeable eyespots on their hindwings as a form of defense against predators.

16. Viceroy Caterpillar

In Iowa, beware of the Viceroy caterpillar, which has a green-and-yellow appearance similar to a monarch butterfly. Their conduct and similarity to kings lead many people to mistake them for such. It’s most likely too late to save your crops if you discover a colony of these caterpillars on your tomato or garden plants. It’s interesting to note that during their larval stage, they feed on ants and lay their eggs on ant nests to survive.

17. Woolly Bear

Making the distinction between moths and butterflies is not too difficult. Moths have thicker antennae than butterflies, which are thinner. Moths are mostly active at night and are not very strong flyers. Moths often have lighter wings underneath and darker wings above, whereas butterflies have brighter colors on top of their wings. The Woolly Bear caterpillar is another less well-known species that can be found in Iowa. It has a brown or black body with three-inch-long white or yellow stripes running down its sides.

18. Cabbageworm

In Iowa, the Cabbageworm, which is sometimes misidentified as a leaf, is a danger to broccoli and cabbage. Usually, these caterpillars emerge in the early spring. By keeping an eye on your garden on a regular basis, you can quickly identify and get rid of them. Remove them and dispose of them by crushing or immersing them in soapy water to stop infestation; do not put them back in the garden. They may destroy your garden if left unchecked, eating away at the leaves and stems until only yellowed remnants are left. The small stature, vivid green hue, and yellow stripes on its flanks are characteristics that set the Imported Cabbage Worm apart.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.

19. Monarch Caterpillar

In Iowa, Monarch Caterpillars (Danaus Paulina) are a species of butterfly found in North America that ranges from Mexico to southern Canada (not including Labrador). They can remain in their caterpillar form for up to ten months, with a wingspan greater than six inches. They leave in October and migrate south through Texas and Mexico, only to come back in March.

20. Gypsy Moth Caterpillar

The Gypsy Moth Caterpillar, also known as the Spongy Moth, is recognized for feeding on the leaves of various trees, including oak, maple, apple, hickory, and more. It has become a persistent pest in many US forests, particularly favoring oak trees as its primary host.

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