Categories College Essays

Caterpillar Types and Identification Guide

Did you find a caterpillar outside, and you’re wondering what kind of butterfly or moth it will turn into? Would you like to raise it to an adult? Find out the name of your caterpillar, what it eats, and what it turns into with the help of this quick and easy caterpillar identification guide.

There are more things you may want to know about the caterpillar you found. Does it sting? Is it rare? This guide will answer your questions about many of the most commonly found caterpillars in North America. Whether you’re a young scientist looking for information for a project, a gardener with big green caterpillars all over your tomatoes, or you simply want to know what that thing crawling across your patio might be, there’s something here for you.

For every species listed, this guide will tell you the following essential information:

  • Does it sting?
  • What does it eat?
  • Will it seriously damage plants or trees?
  • Is it rare?
  • What does it turn into?
  • Can you raise it to an adult?

If you still have questions about identifying the caterpillar you found, there are good internet sources that are species-specific and can give you more detail.

This guide to garden-eating insects might help!

Caterpillars are the larval stage of Lepidoptera, commonly known as butterflies and moths. They spend their days eating and storing energy for the adult butterfly or moth that they will become. Caterpillars are well-adapted to their natural surroundings. Most of them are camouflaged, so even though they’re all around us, we never see most of them. They are so perfectly disguised, or have such secretive habits, that we walk right by them without ever knowing they’re there. But they are!

Most caterpillars live their lives quietly eating leaves (and, of course, pooping). They rarely do any damage to the plant they live on. Sometimes, however, caterpillars can seriously harm trees and other plants. The gypsy moth caterpillar is a serious pest of oak forests in the northern US. Other caterpillars attack garden plants. If you grow tomatoes, chances are good you’ve come across the Tomato Hornworm, a big green monster that can destroy a tomato plant in less than a week.

Does your caterpillar sting? Is it a threat to children or your pets? Find out quickly with this OWLCATION STINGING CATERPILLAR GUIDE.

If you’re wondering about your caterpillar’s life, food, behavior, and habits, you should have a look at my CATERPILLAR Q&A article here on Owlcation!

This cool caterpillar is always found on some species of milkweed (Asclepias species). They aren’t too hard to spot, with their bright stripes of black, white, and yellow. The milkweed that monarchs feed on is protected by having poisonous sap, which in turn makes the monarch caterpillar poisonous to any potential predators. Not a bad form of protection! They are brightly colored and turn into one of the most beautiful and popular of all butterflies: the monarch. Check it out, below!

The Basics:

  • Does it sting? No.

  • What does it eat? Milkweeds

  • Will it seriously damage plants or trees? No — milkweed is a common roadside plant.

  • Is it rare? No, although pesticide run-off is threatening its foodplant!

  • What does it turn into? The beautiful monarch butterfly.

  • Can you raise it to an adult? Yes, it does well in captivity.

You can easily make a big difference simply by planting a few milkweed plants in your yard. Monarchs will visit the flowers and lay eggs on the leaves. Milkweed is the only kind of plant Monarch caterpillars eat, and without them they’ll die. Pesticides used by modern agriculture can poison and kill milkweed plants, so you can help Monarchs by planting milkweeds yourself. The seeds are FREE. This article shoes you how to get started. THANK YOU!

This caterpillar looks a lot like the monarch caterpillar (above) — and that may not be an accident. The monarch is most likely “protected” by the bitter sap of the milkweed plant that it eats because some of the toxic compounds in the sap become incorporated into the insect’s tissues.

The black swallowtail caterpillar eats the leaves of carrots and other Umbelliferae species, which gives them little protection. But sometimes just looking like you’re poisonous can be protection enough — that’s the basis of one major form of mimicry. It’s thought that the black swallowtail caterpillar mimics the monarch caterpillar so birds and other predators might leave it alone, putting a mistaken identity to good use!

These caterpillars can be kept in a safe, unbreakable habitat designed for raising caterpillars. Make sure you give them plenty of the host plant—for this species, carrot or dill—that you found them on.

This attractive caterpillar turns into a beautiful, big butterfly known as the black swallowtail.

The Basics:

  • Does it sting? No

  • What does it eat? Parsley, carrots, and dill

  • Will it seriously damage plants or trees? Sometimes they can eat a lot of carrot greens.

  • Is it rare? No, but it isn’t always common in all areas.

  • What does it turn into? The gorgeous black swallowtail butterfly.

  • Can you raise it to an adult? Yes, if you give it an upright stick to pupate on.

This species is quite common in some parts of the United States. You’ll most likely find it wandering around looking for a safe place to make a cocoon. The moth is a pretty brown-and-cream color and is part of the genus Halysidota, which includes many similar species found all over the US. In some ways, it looks cooler as a caterpillar than as a moth, but that’s just my opinion! Check out the Sycamore Tussock Moth below and let me know what you think.

The Basics:

  • Does it sting? No, although the fur may be irritating to sensitive skin.

  • What does it eat? Sycamores and related plants.

  • Will it seriously damage plants or trees? No, it seldom occurs in enough numbers to do damage.

  • Is it rare? No.

  • What does it turn into? A cool, pale-brown tiger moth.

  • Can you raise it to an adult? Yes — it will spin a cocoon in the container.

This is a BIG caterpillar, growing up to five inches long. And it looks amazing as well — check out the orange and blue “clubs” on it. The cecropia caterpillar feeds on oak, willow, and maple, among other trees and bushes. It can be found wandering around in late summer as it looks for a place to spin its tough, brown cocoon. This spectacular caterpillar turns into an even more spectacular moth. The cecropia moth, below, is a bat-sized beauty that belongs to the group of “giant silk moths.” These are among the largest Lepidoptera in North America.

The Basics:

  • Does it sting? No, despite all the tubercles and spines.

  • What does it eat? Many plants, including privet, ash, birch, oak, and walnut.

  • Will it seriously damage plants or trees? Not usually.

  • Is it rare? No, but it appears to be becoming less common.

  • What does it turn into? A huge, beautiful moth.

  • Can you raise it to an adult? Yes — this species does well in captivity.

This is another big caterpillar — about the size and thickness of your thumb. It’s closely related to the cecropia moth (above). Polyphemus caterpillars eat maple, birch, willow, and several other trees but are seldom abundant enough to cause any real damage. As big as they are, they are really hard to see among the foliage when they’re resting. As with many caterpillars that leave the food plant to spin a cocoon, Polyphemus are sometimes seen wandering around in late summer. This caterpillar spins a tough, brown, oval cocoon that you may find attached to bushes and plants around your house during the winter.

The polyphemus moth, below, has large eyespots that look like an owl and may scare predators away. Another example of mimicry!

The Basics:

  • Does it sting? No.

  • What does it eat? Many plants, including birches, maples, oak and walnut.

  • Will it seriously damage plants or trees? Not usually.

  • Is it rare? No — this is one of the more common giant silk moths.

  • What does it turn into? A huge, beautiful moth.

  • Can you raise it to an adult? Yes.

These little guys are often seen hot-footing it across the road in rural areas of eastern North America. They belong to the family of tiger moths (Arctiidae), which includes many attractive and widespread species. Woolly bears are the larva of the Isabella tiger moth, Pyrrharctia isabella, and they feed on a number of common plants found in second-growth areas and roadsides. When you see them hustling across the road, they are looking for a good place to spend the winter; this species hibernates under rocks or logs, emerging in the spring to pupate. The moths emerge in early summer.

The Basics:

  • Does it sting? No, although the fur can be irritating to sensitive skin.

  • What does it eat? Just about anything, from oak trees to dandelions.

  • Will it seriously damage plants or trees? No.

  • Is it rare? No.

  • What does it turn into? A very pretty but seldom-seen moth.

  • Can you raise it to an adult? Not easily, since it overwinters as an adult and needs a pretty specific environment.

Then you’ll REALLY like my guide to some of the most commonly seen beetles in North America. Here’s a link: MEET THE BEETLES.

This is one of the most commonly encountered of all North American caterpillars. They eat a wide variety of common plants, many of them considered weeds, and they make no real effort to hide — you can often find them on the top of a leaf in the middle of the day, happily eating. They are typically pale yellow or orange, but some individuals are much darker. The fur is thick but not spiny, and they are very “firendly” — they don’t seem to mind being handled and will harmlessly crawl over your hands (some people with super-sensitive skin may have a mild reaction to the fur). The adult is a beautiful white moth that you may find in the summer around your porch lights.

The Basics:

  • Does it sting? No, although the fur can be irritating to sensitive skin.

  • What does it eat? Mostly low plants and “weeds.”

  • Will it seriously damage plants or trees? No.

  • Is it rare? No.

  • What does it turn into? A very pretty white moth.

  • Can you raise it to an adult? Yes.

This species, Automeris io, belongs to the group of giant silk moths that also includes the cecropia and polyphemus moths. This is one of the few caterpillars in our area that has irritating spines for protection, which really interested me when I was a kid. I had read all about the animal’s “stinging spines” in my trusty Golden Nature Guide. I found one when I was about twelve and brushed the spines against my arm on purpose to see what all the fuss was about. Did it sting? Yes!

This beautiful caterpillar turns into a beautiful moth. The false eye-spots on the hind wing are very realistic, and come complete with reflected-light markings, making them extra realistic.

The Basics:

  • Does it sting? YES. This species is protected with venomous spines.

  • What does it eat? Many plants, including roses and other garden plants.

  • Will it seriously damage plants or trees? Not usually an issue.

  • Is it rare? No, but it is generally not common.

  • What does it turn into? The striking io giant silk moth.

  • Can you raise it to an adult? Not advised.

These huge caterpillars can often be found chowing down on your tomato plants, often to the point where the entire plant is eaten. The tobacco and tomato hornworms are very similar and often eat both plants, as well as sweet potatoes and other crops. They produce similar moths: huge brown bombers that are such good fliers they have earned the nickname “hawk moths.”

The Basics:

  • Does it sting? No. The horn on the tail end appears to be only for show.

  • What does it eat? Tomatoes, tobacco, and many other plants.

  • Will it seriously damage plants or trees? Yes — this species can be a serious pest.

  • Is it rare? No, very common, even in cities.

  • What does it turn into? A big strong moth known as a “hawk moth.”

  • Can you raise it to an adult? Yes, without much difficulty.

I am often asked about killing caterpillars that are destroying garden plants. I myself prefer to pick them off by hand and smash them into my compost pile, but sometimes that’s not practical. On occasion I will use a product called DIATOMACEOUS EARTH. Diatomaceous Earth kills pest insects and is safe for the environment — in fact, it’s one of the more common substances found in nature. The way it works is pretty mind-blowing.

How Diatomaceous Earth Works

Diatomaceous Earth is refined from dirt found in the bottom of old ocean, lake and stream beds. It’s full of the fossilized exo-skeletons of microscopic animals called diatoms. The skeletons of these animals are made out of silica, the same basic component of sand (and the silicon that supplies Silicon Valley with material for all of our computer chips).

Here’s where it gets interesting. Diatomaceous Earth is not toxic, and is not a poison — it kills insects because when they crawl over it, the jagged silica shells left behind by the diatoms make little scratches and cuts on the insect’s underside. This damage is typically fatal.

Human Safety

Diatomaceous Earth is considered safe for humans, and much of it is “food grade” and actually offered as a dietary supplement. I avoid breathing it, but that’s not too difficult since you’re typically outside when you apply it. All things considered, this product is the thing you want when you have an out-of-control caterpillar problem.

This cool-looking little guy is the larval stage of the tiger moth Euchaetes egle. There are relatively few Lepidoptera species that feed on milkweed, which has poisonous sap that may make the caterpillars themselves poisonous to birds. Like the monarch, milkweed tiger moth caterpillars eat nothing but milkweed and spend all of their time on the plant, living and moving in small groups of up to ten. They’re not at all hard to find on the host plant — their bright coloring is thought to be a kind of warning to predators not to even bother eating them.

For such a showy caterpillar, the adult milkweed tiger moth is pretty plain — unmarked, light gray wings with a spotted abdomen.

The Basics:

  • Does it sting? No, but the fur may be irritating.

  • What does it eat? Milkweeds.

  • Will it seriously damage plants or trees? Not usually, although it will eat a fair amount.

  • Is it rare? No.

  • What does it turn into? A very plain gray moth.

  • Can you raise it to an adult? Not easily, since they occur in large groups and need lots of fresh milkweed.

This is the dreaded gypsy moth caterpillar, Lymantria dispar, which can multiply out of control and strip entire oak trees down to the branch. In some cases, whole forests lose their leaves to hordes of these caterpillars. Walking into a forest under siege from gypsy moth caterpillars, you can hear the sound of millions of tiny jaws working away, eating every leaf in site. Attempts have been made to control this caterpillar by spraying infested forests with a kind of bacteria that kills the caterpillars. While this can be effective, the bacteria is known to kill many other species of caterpillars in addition to the gypsy moth. It’s a high price to pay to rescue trees that will likely eventually survive anyway!

The Basics:

  • Does it sting? No, although the spines are sharp and stiff.

  • What does it eat? Everything, and a lot of it.

  • Will it seriously damage plants or trees? Yes — this is one of the most serious insect pests on the planet.

  • Is it rare? No.

  • What does it turn into? The gypsy moth.

  • Can you raise it to an adult? Yes, but please don’t.

This pretty blue and brown caterpillar is often found in large numbers in oak forests. They can be a pest, but not on the level of the dreaded gypsy moth, which can defoliate an entire forest in a matter of weeks. They get the name “tent caterpillar” because the group of insects they belong to tend to make silk webs or mats on the branches and trunks of the host trees. They eat a variety of trees, especially wild cherry — the cyanide in the cherry leaves may be the reason that this caterpillar can spit “tobacco juice” that contains a small amount of cyanide.

The moth that this caterpillar turns into is a pretty fawn brown color with subtle stripes and a furry body.

The Basics:

  • Does it sting? No, although it can spit toxic “juice.”

  • What does it eat? Forest trees such as wild cherry.

  • Will it seriously damage plants or trees? Yes, it can.

  • Is it rare? No, very common.

  • What does it turn into? A pretty brown moth.

  • Can you raise it to an adult? No, since it needs a large tent to live in with dozens of other caterpillars.

When I was a boy, I always hoped to find one of these amazing creatures munching on the leaves of the hickory trees in our neighborhood. I never did, though — they are not all that common, and live mostly in the South. My bad luck to live in the North! The hickory horned devil is likely the largest, and certainly the fiercest-looking, caterpillar in North America. Full-grown, they are nearly half a foot long, and will rear up and make a clicking sound if you bother them. They’re totally harmless, though, like pretty much all caterpillars.

The hickory horned devil turns into the regal moth, a gigantic, beautiful animal that most people will never see in nature.

The Basics:

  • Does it sting? No, even though it looks really fierce.

  • What does it eat? Walnut, oak, persimmon, and hickory.

  • Will it seriously damage plants or trees? Not usually.

  • Is it rare? Common in the southern states.

  • What does it turn into? A huge, beautiful moth — in terms of mass, it’s the biggest in North America.

  • Can you raise it to an adult? Yes, although it pupates in soil (no cocoon).

This bright orange beauty is one form of a somewhat common type of sphinx moth larva — the other form is green, and while beautiful, is not quite as striking as this one. I’ve included this caterpillar mainly because I think it’s so beautiful – as is the moth it turns into. This caterpillar in the illustration may be a tropical version of the North American pandorus species — it’s a little hard to tell. But if you find one, you can be sure you’ve found a truly special insect.

The Basics:

  • Does it sting? No.

  • What does it eat? Grape and virginia creeper, among other plants.

  • Will it seriously damage plants or trees? Not usually.

  • Is it rare? This species is not rare but it is seldom seen.

  • What does it turn into? A truly gorgeous moth.

  • Can you raise it to an adult? Yes.

This species feeds only on catalpa trees, which are very common in the South and becoming more so in the North. Catalpa trees have big, pale green leaves and form seed pods in the fall. They are common ornamental trees and can be found in both city and suburb.

The catalpa sphinx can really do a number on an infested tree. But there is also a type of parasitic wasp whose eggs turn into little wasp larvae that eat the caterpillar from the inside out. This kills the caterpillar, as you might guess! If it manages to avoid such an unpleasant fate, it turns into the moth pictured below.

The Basics:

  • Does it sting? No.

  • What does it eat? Catalpa leaves, and a lot of them.

  • Will it seriously damage plants or trees? Yes, it has been known to strip all the leaves from a tree.

  • Is it rare? Common in the southern United States.

  • What does it turn into? A large brown moth.

  • Can you raise it to an adult? Yes.

This caterpillar eats elm leaves and is known in some places as “the spiny elm caterpillar.” It is the larval stage of one of the best-known butterflies in the world, the mourning cloak. This beautiful insect is native to the US and Europe. In the UK, this species is incredibly rare, and entomologists can spend a lifetime waiting for one to show up (it’s known as “the Camberwell Beauty” in England). Up close, the upper side of the mourning cloak is gorgeous. The underside is considerably more drab; the dark colors give the insect its common name because early entomologists thought it looked like the drab cloaks worn by mourners at funerals.

Mourning cloaks often winter in a shelter and begin flying on the first warm days of spring. Keep an eye out for these big, beautiful butterflies on warm spring days, even when there are still patches of snow on the ground.

The Basics:

  • Does it sting? No, although the spines are sharp.

  • What does it eat? Elm leaves.

  • Will it seriously damage plants or trees? Not usually.

  • Is it rare? Not in North America, but in England it is very rare.

  • What does it turn into? A gorgeous burgundy and yellow butterfly

  • Can you raise it to an adult? Yes, if you give it plenty of fresh leaves.

This cool caterpillar has irritating “fur” that it spins into its cocoon. The black hair pencils may act as fake antennae, making the insect appear larger or more threatening than it really is. This caterpillar feeds on oaks and other trees, and can be very common in the late summer and early fall as it crawls around looking for a place to spin its oval cocoon.

The Basics:

  • Does it sting? No, but the fur can be irritating.

  • What does it eat? A lot of trees, including ash, birch, elm, maple, and oak.

  • Will it seriously damage plants or trees? No.

  • Is it rare? No, quite common.

  • What does it turn into? A pretty gray moth.

  • Can you raise it to an adult? Yes, especially if you find one wandering around in late summer looking for a place to spin a cocoon.

This rather plain caterpillar turns into one of our most spectacular butterflies, the tiger swallowtail (Pterourus glaucus). It is sometimes seen crawling down the trunks of ash and cherry trees in early summer, looking for a place to pupate. This caterpillar overwinters as a very young larvae, rolled up in a little leaf shelter, to emerge in the spring and resume eating and growing. The adult butterflies are a common sight in parks and gardens, yellow and black beauties that soar high among the treetops, looking for mates and a place to lay their eggs.

The Basics:

  • Does it sting? No.

  • What does it eat? Ashes, wild cherry, apple, and other trees.

  • Will it seriously damage plants or trees? No.

  • Is it rare? No, very common; subspecies occur throughout North America.

  • What does it turn into? A big beautiful tiger-striped butterfly.

  • Can you raise it to an adult? Yes.

These cool-looking caterpillars produce a quite plain and inconspicuous moth. They eat almost anything, including some decorative trees like hawthorn that cities tend to plant along roads and in plazas. Tussock moth caterpillars get their name from the little tufts of fur along their backs; apparently these are called “tussocks” in some parts of the world.

The Basics:

  • Does it sting? No, but it has stiff hairs that are irritating to some people.

  • What does it eat? Many trees, including ornamentals planted in urban areas.

  • Will it seriously damage plants or trees? Yes, it can be a real problem.

  • Is it rare? No.

  • What does it turn into? A small brown moth with a white mark on its wing.

  • Can you raise it to an adult? Yes, quite easily.

With its awesome pompadour and general slug-like build, this animal is sometimes referred to as the “Elvis Caterpillar.” Puss moth caterpillars belong to the Megalopygidae family, which has a fair number of interesting-looking caterpillars. Many of these caterpillars have stinging hairs — including the puss moth, which sometimes drops out of trees onto unlucky passersby! The sting of the puss moth is usually mild, though sensitive individuals can develop a more intense reaction.

Megalopygidae moths are relatively uncommon, and if you see one you’re lucky — but don’t touch!

Nota bene:There’s a moth in the UK called the Puss Moth, but it’s in a different family (Notodontidae) and the caterpillars do not have stinging hairs.

The Basics:

  • Does it sting? YES. This caterpillar has one of the worst stings of any Lepidopteran.

  • What does it eat? Oak, elm, and wild plum.

  • Will it seriously damage plants or trees? No.

  • Is it rare? It’s not very common, but it’s not rare.

  • What does it turn into? An interesting-looking insect called a “flannel moth.”

  • Can you raise it to an adult? Best not to try!

This is a cool caterpillar with fake snake eyes. The effect is even better when it sticks out its “osmeteria,” a red, forked organ that it can stick out from behind its head when it’s feeling bothered. The osmeteria looks a lot like the forked tongue of a snake, and it also smells bad. Pretty good defense for an otherwise tasty caterpillar! This one turns into the big, beautiful spicebush swallowtail.

The Basics:

  • Does it sting? No.

  • What does it eat? The spicebush, and other members of the genus Lindera.

  • Will it seriously damage plants or trees? No.

  • Is it rare? No, but it’s not very common in the northern states.

  • What does it turn into? A beautiful butterfly.

  • Can you raise it to an adult? Yes.

Raising a caterpillar to the adult stage is a pretty cool science/home learning experience. You get to witness one of the natural world’s most amazing events: the change from a caterpillar to a butterfly. Plus, you’ll have the chance to definitively identify the insect you found.

Along the way, you’ll learn about food plants, life stages, cocoons and chrysalises, parasites, and how scientists work in the lab with insects. Who knows — there’s a chance you or your little ones might start on the path to becoming a scientist some day.

If raising caterpillars sounds like a fun project, then I’d recommend housing them in a container designed to keep caterpillars safe and well-fed, like one of the products made by InsectLore caterpillar habitats. It’s critically important that you keep them fed with fresh leaves from the exact plant on which you found them. If you found them wandering around, they’re likely about to pupate. Some leaves or a paper towel on the bottom of the habitat will give them a place to cocoon.

These are some places you can find information about caterpillars and insects:

https://owlcation.com/stem/caterpillar-identification

http://www.panamainsects.org/

mothphotographersgroup.msstate.edu

Maybe you’ll find it on one of these fine Owlcation guides:

Striped Caterpillar Identification — If your caterpillar has stripes, you might find it here.

Furry Caterpillar Identification — Many moth caterpillars and a few butterfly caterpillars are furry or hairy. This guide includes some of the ones you’re most likely to come across

Green Caterpillar Identification — Green is the most common color for caterpillars, since they live among leaves and they can avoid predators by blending in.

Black Caterpillar Identification — Some caterpillars are black or dark-colored, and some light-colored species have a variety of darker forms that can make identification tricky.

Insect Identification — An entertaining and authoritative guide to the insects you’re most likely to find in your garden or around your home.

And if you can’t find it anywhere, there’s a chance that it’s actually a beetle larva. Have a look at my article about beetles right here.

Good luck!