Caterpillar Types and Identification Guide
I Found a Caterpillar. What Will it Turn Into?
Did you find an awesome-looking caterpillar outside? Identify it with the help of this guide! Is your caterpillar rare? Does it sting? What does it eat? What does it turn into? Here you will find photographs and descriptions of many of the different caterpillar types found 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.
You Can Raise Your Caterpillar to a Butterfly or Moth
It's easier than you think to keep the caterpillar you found and raise it to an adult. Start with a tupperware container or a jar, and fresh leaves from the plant you found it on. Sometimes the caterpillar you found is on its way to make a cocoon or chrysalis, and it won't be interested in eating. Keep it with leaves from a few of the nearest plants just in case, and it will probably begin its transformation in a few days.
The best way to keep a caterpillar alive is with a safe, unbreakable habitat designed for raising caterpillars. Keep a paper towel on the bottom and clean out poops and old leaves every two days. They don't need extra water or direct sunlight.
Caterpillars: An Overview
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.
Amazing Insects of Panama
Does This Caterpillar Sting?
While most caterpillars rely on camouflage and distasteful chemicals for protection, some have spines and hairs that can sting you.
I hope you enjoy this guide and find it useful. From six-inch long beasties with curved horns and jagged spikes to the familiar, furry wooly bear, here are some of the most commonly encountered caterpillars of North America.
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!
Black Swallowtail Caterpillar
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.
Black Swallowtail Butterfly
Sycamore Tussock Moth Caterpillar
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 genus Halysidota, which includes many similar species found all over the US. In some ways, it looks better 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.
Sycamore Tussock Moth
Which Do You Prefer?
Do you think the Sycamore Tussock moth or caterpillar looks cooler?
This is a BIG caterpillar, growing up to five inches long. And it looks amazing as well! Check out the orange and blue tubercles 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.
Polyphemus Moth Caterpillar
This is another big caterpillar -- about the size and thickness of your thumb. Polyphemus eat maple, birch, willow, and several other trees but are seldom abundant enough to cause any 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 the eaves 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!
Wooly Bear Caterpillar
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 has many attractive and far-flung members. Wooly 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.
As with the sycamore tussock moth, I think the wooly bear moth looks much cooler as a caterpillar. The moth's grey-ish brown coloring makes it easy to camouflage itself, I'd rather look at the caterpillar's snazzy black and yellow coloring.
Wooly Bear Tiger Moth
Io Moth Caterpillar
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 actually brushed the spines against my arm on purpose to see what all the fuss was about. Did it sting? Yes -- kind of like stinging nettles, not intense, but the kind of thing you don't want to repeat. A good protection for a caterpillar to have!
It turns into a beautiful-looking moth as well. The eye-spots look like little pieces of jewelry. Check it out below!
Tomato and Tobacco Hornworms
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."
Tobacco and Tomato Hornworm Moth
Milkweed Tiger Moth Caterpillar
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.
Milkweed Tiger Moth
Gypsy Moth Caterpillar
This is the dreaded gypsy moth caterpillar, Lymantria dispar, which can multiply out of control and strip entire oak trees down to the trunk. In some cases, entire 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 entire 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!
Forest Tent Caterpillar
This pretty blue and brown caterpillar is often found in large numbers in oak forests. They can be a pest on the level of the dreaded gypsy moth, and like the gypsy moth 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.
The moth that this caterpillar turns into is a pretty fawn brown color with subtle stripes and a furry body.
Forest Tent Caterpillar Moth
Hickory Horned Devil
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.
Regal Moth (Hickory Horned Devil Moth)
Pandorus Sphinx Moth
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.
Pandorus Sphinx Moth
Catalpa Sphinx Moth Caterpillar
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.
Catalpa Sphinx Moth
Mourning Cloak Caterpillar
This caterpillar eats elm 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 caterpillar 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.
Mourning Cloak Butterfly
American Dagger Caterpillar
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.
American Dagger Moth
Tiger Swallowtail Caterpillar
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.
Tiger Swallowtail Butterfly
White-Marked Tussock Caterpillar
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.
White-Marked Tussock Moth
This habitat is as close as I could find to the ones used in labs around the world. This unit comes from one of the best-known biological supply houses in the country. It's not a toy and has excellent, lab-quality features.
Puss Moth Caterpillar
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.
Puss Moth Caterpillar Moth
Spicebush Swallowtail Caterpillar
This is a cool caterpillar with fake snake eyes. The effect is even better when it sticks out its "osmeterium," a red, forked organ that it can stick out from behind its head when it's feeling bothered. The osmeterium 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.
Explore More by Raising Caterpillars to Adulthood
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:
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