26 Weird (but COMMON) Caterpillars in Maine (2025)
What kinds of caterpillars can you find in Maine?
Caterpillars are some of the MOST fascinating insects in the world! It always amazes me that caterpillars eventually turn into butterflies or moths.
There are hundreds of different caterpillar species found in Maine!
Since it would be impossible to list them all in one article, I chose the 26 most interesting and common ones to share with you. 🙂
#1. Monarch Caterpillar
- Danaus plexippus
Identifying Characteristics:
- This famous caterpillar is plump with black, white, and yellow bands.
- Its legs and pro-legs are pronounced, and each end of its body has spindly black tentacles.
- The Monarch’s preferred host plant is milkweed.
Like the adult butterfly, the Monarch is one of the most well-recognized caterpillars in Maine!
Their distinctive stripes and tentacles make them look cartoonish. But this highly visible coloring sends a message to predators: Back Off!
Monarch Caterpillars are toxic to most animals, and at the very least, taste bad! This poison comes from their diet, which is almost entirely made up of milkweed. Toxins from the milkweed plant stay in the caterpillar, producing a bitter taste and poisonous effects.
If you have milkweed in your yard or nearby, your chance of finding Monarch Caterpillars is excellent! Honestly, there is nothing more fun than finding these colorful insects on our milkweed plants and getting to watch them transform into adults!
#2. Cabbageworm
-
Pieris rapae
Identifying Characteristics:
- Coloring is light green with small yellow dots along the sides.
- This species is small and relatively thin and appears velvety.
- Cabbageworms’ host plants are Brassicas, including cabbage, kale, broccoli, and chard.
In Maine, this species is often called the Imported Cabbageworm because it isn’t native to North America. It was introduced in shipments of cabbage and other brassica plants and soon became an invasive species.
Cabbageworms are considered agricultural pests and can do severe damage to crops to their host plants. Cabbage, brussels sprouts, broccoli, and cauliflower are all susceptible to damage. For a home gardener, the best way to deal with Cabbageworms is to prevent a large infestation. Plant covers, regular weeding, and varied plantings can all help with preventing this hungry invader!
One reason Cabbageworms are so damaging is that they are voracious eaters! They can easily skeletonize entire plants, eating everything but the toughest stems and midveins. Boring through heads of cabbage and making huge dents in broccoli are no problem for this Very Hungry Caterpillar!
Cabbageworms grow into Cabbage White Butterflies, which are one of the most abundant butterflies in Maine! If you see a white butterfly in the spring, chances are it’s a Cabbage White!
#3. Woolly Bear
- Pyrrharctia isabella
Identifying Characteristics:
- Coloring is black with a wide rusty-red band in the middle.
- As its name suggests, the Woolly Bear caterpillar is covered in dense, coarse hairs.
- Transform into Isabella Tiger Moths.
- Woolly Bears are generalist feeders, meaning they will live on and eat nearly any plant!
As a kid, I can remember hearing tons of stories about Woolly Bear caterpillars – and the coolest part about them is that most of the stories are true! One myth you might have heard is that Woolly Bears can predict the type of winter we’ll have. Unfortunately, this one isn’t true. But there’s plenty of other interesting facts about this cute little caterpillar!
The most fascinating thing about Woolly Bears is the way they hibernate.
That’s to say, they don’t hibernate at all! Instead of burrowing or pupating to escape the cold, Woolly Bears allow themselves to freeze solid. They have a unique chemical in their blood that allows them to thaw out and continue in the spring as if nothing happened!
You may have heard that Woolly Bear Caterpillars are venomous, but this isn’t entirely true. Their hairs don’t contain any toxins or irritants, but some people are sensitive to the hairs and may get a slight rash if they touch one. It’s best to observe the species without touching them, just in case.
Woolly Bear Caterpillars and their adult-form, Isabella Tiger Moths, are found in incredibly varied climates, even the Arctic! Because they will eat almost anything, including herbs, tree leaves, and grasses, they can be found pretty much anywhere plants are growing. Look for them in groups near the base of plants.
Just don’t expect them to take over for your meteorologist! 🙂
#4. Viceroy Caterpillar
- Limenitis archippus
Identifying Characteristics:
- The coloring is mottled brown or green and white to resemble bird droppings.
- Two dark-colored horns on the head and small spines on the body.
- The chrysalis also resembles bird droppings hanging from a tree branch.
- The preferred host plants of Viceroy Caterpillars are willow, poplar, and cottonwood trees.
Viceroy Caterpillars are one of the ugliest caterpillars in Maine!
This is by design; their lumpy, mottled appearance makes them look like bird droppings, warding off predators!
Interestingly, this isn’t the Viceroy’s only protection against predators. Viceroy Caterpillars eat plants that are rich in salicylic acid, which they store in their bodies. When predators try to eat them, they are rewarded with a strong, bitter flavor and an upset stomach. One taste and they learn to stay away!
Viceroy Caterpillars primarily live in open forests or fields, and they’re found across many different climates. Look for them during spring and summer, which is when the adults typically mate.
Interestingly, Viceroy and Monarch Caterpillars look almost identical.
#5. Large Maple Spanworm
- Prochoerodes lineola
Identifying Characteristics:
- Gray-brown coloring with small black spots scattered on the body. Often this species has a bark-like pattern.
- Thin and stick-like with a knob on each end.
- Large Maple Spanworms use a huge variety of plants and trees as hosts: birch, maple, cherry, apple, oak, poplar, walnut, and willow trees; geranium, soybean, blueberry, and currant plants; and grass.
This species has one of the best camouflages of any caterpillar in Maine!
Large Maple Spanworms look exactly like a bit of twig on a tree, even from up close! So, it’s hard to imagine any predator observant enough to try and eat one, which is precisely its goal.
Their camouflage is the only defense Maple Spanworms have because they aren’t poisonous. They’re a favorite snack for determined birds!
When they’re not imitating sticks, Large Maple Spanworms have an interesting way of getting around! They plant their front legs, arch their back in the air, and bring their back legs forward to meet their front. Then, they throw their front forward and repeat the whole process. They’re one of many caterpillars that move like this, earning them nicknames like inchworm, looper, or spanworm.
Large Maple Spanworm Moths are just as adept at camouflage as their larva – they look exactly like dead leaves clinging to a branch!
#6. White-Marked Tussock Caterpillar
- Orgyia leucostigma
Identifying Characteristics:
- Black and yellow stripes run the length of the body with a large red spot on the head.
- Many tufts of hair-like spines.
- White-Marked Tussock Caterpillars will use nearly any coniferous or deciduous tree as a host!
The White-Marked Tussock Caterpillar wins the prize for the most interesting haircut!
Tufts of spiky hair give this caterpillar the look of having antennae, a tail, and spiky sides. In addition, four white tufts look like paintbrushes sprouting from its back. Talk about a unique style! And it doesn’t stop there – on the adult White-Marked Tussock Moth, the Antennae themselves are covered in fur!
The hairs on the White-Marked Tussock Caterpillar and its relatives are called urticating hairs, meaning they can cause a rash. Although it may be annoying and itchy, the inflammation isn’t dangerous, and this species is not venomous.
White-Marked Tussock Caterpillars sometimes have population outbreaks, where a local population swells exponentially. When these outbreaks happen, it’s common for colonies of the caterpillars to eat all of the leaves off of a tree, severely damaging them. Fortunately, there are quite a few natural predators that aren’t bothered by its hairiness and they are able to feast!
Viral infections eventually stop many population outbreaks of White-Marked Tussock Caterpillars. Alphabaculovirus, which is a class of viruses that infect and kill many caterpillars, moths, and butterflies, is mostly to blame. Infections spread quickly through White-Marked Tussock Caterpillar populations because they live closely together on the same host plant. The virus causes rapid sickness and death among infected individuals.
#7. Milkweed Tussock Caterpillar
- Euchaetes egle
Identifying Characteristics:
- Tufts of black and white hairs cover the body, with one line of black-centered orange tufts along the back.
- The body is relatively thin and up to 1.5 inches long.
- As its name suggests, this species’ preferred host is Milkweed.
Despite looking very different, Milkweed Tussock Caterpillars in Maine have a lot in common with Monarch caterpillars!
Milkweeds are the preferred host plant for both species. However, the really interesting thing about them isn’t what they eat; it’s why! Milkweed Tussock Caterpillars store a poisonous chemical from milkweed called cardiac glycoside in their body.
It doesn’t harm the caterpillar, but it does an effective job of making the caterpillar both disgusting and dangerous for many predators! In fact, Blue Jays have been known to vomit after eating just one of these furry little caterpillars.
The fascinating thing about cardiac glycoside is it stays in the caterpillar’s body through its transformation into a moth. So, even though Milkweed Tussock Moths don’t eat milkweed, they still have the benefits that the caterpillar’s diet created!
#8. Banded Tussock Caterpillar
- Halysidota tessellaris
Identifying Characteristics:
- Coloring is pale cream, yellow, light brown, or white. Black tufts on the head and rear end stick out further than the white hairs.
- One darker line runs down the center of the back.
- Its preferred host plants are alder, ash, and fruit trees.
The Banded Tussock Caterpillar is similar in appearance to other Tussock Caterpillars, with one main difference – it’s actually not a true Tussock Caterpillar at all!
This master of disguise is actually the larva of the Pale Tiger Moth. Unlike true Tussock Caterpillars, this species isn’t venomous. However, some people are extra sensitive to the hairs that cover its body and may still get a rash. Even if you’ve identified a caterpillar as a Banded Tussock, it’s best to observe, not handle, the caterpillar!
Banded Tussock Caterpillars have an interesting way of forming their chrysalis when it’s time to transform into adult moths. They use their hairs to make a soft, felted cocoon that keeps them from freezing over winter!
#9. Giant Leopard Moth Caterpillar
- Hypercompe scribonia
Identifying Characteristics:
- Black bristles cover the entire body with red rings evenly spaced.
- This caterpillar is often found curled in a ball, which is its defensive posture.
- Giant Leopard Moth Caterpillars eat the fruit and leaves of cherry, cabbage, dandelion, maples, orange, sunflowers, violets, and willows.
This unassuming caterpillar is hiding a big secret – it grows up to be a large and absolutely beautiful moth!
If you find one, you might mistake the Giant Leopard Moth Caterpillar for a Woolly Bear Caterpillar. It’s easy to confuse the two, and this species is sometimes called the Giant Woolly Bear! But the red rings on the Giant Leopard Moth caterpillar are narrower and run the length of its body.
As Giant Leopard Moth Caterpillars form a chrysalis, they shed the exoskeleton with their trademark bristly hairs. This makes the cocoon look like it’s wearing a large wig! 🙂
Adult Giant Leopard Moths are huge, up to 3.5 inches across, and bright white with a spotted pattern. They are intimidating moths, especially if you’re not expecting to find one. I recently saw one up close in my garage, and I certainly won’t forget the encounter anytime soon!
#10. Parsley Caterpillar (Black Swallowtail)
- Papilio polyxenes
Identifying Characteristics:
- The coloring is bright green, with rings of black and yellow dots down the length of the body.
- The head and thorax are slightly larger than the back, and the legs and pro-legs are pronounced and visible even from a distance.
- Parsley plants are the preferred host of this species.
Parsley Caterpillars, sometimes called parsley worms, are the larva of the Black Swallowtail butterfly. They get their name from their preferred host and favorite snack, the parsley plant.
At first glance, it’s easy to mistake a Parsley Caterpillar for a Monarch. But, the coloring is slightly different, and the stripes on the Monarch Caterpillar are a bit thinner. It would also be unusual for a Monarch Caterpillar to eat parsley or other garden herbs since they eat milkweed almost exclusively!
If you’re a gardener, you might consider Parsley Caterpillars a bit of a nuisance since they can decimate a parsley plant quickly. But, if you plant some extra, you’ll be rewarded with sightings of the beautiful Black Swallowtail butterfly in a few weeks!
#11. Eastern Tiger Swallowtail Caterpillar
-
Papilio glaucus
Identifying Characteristics:
- The coloring is bright green with two large eyespots in white, black, and blue.
- The thorax is much larger than the middle and tail, giving the caterpillar the look of an enlarged head.
- The favorite host plants of this species are the tulip tree and wild black cherry.
This species is one of the strangest-looking caterpillars in southern Maine!
The appearance of Eastern Tiger Swallowtail Caterpillars is so unique they inspired a Pokemon! Caterpie (the Pokemon) has the same features, including its horn-like Osmeterium, bulbous thorax, and large round eyespots. I consider this to be quite an honor! 🙂
This caterpillar’s primary defense is mimicry, using its unique shape and coloring to imitate a snake’s head. Additionally, as a young caterpillar, its color is brown and white to mimic bird droppings!
Interestingly, the adult Eastern Tiger Swallowtail Butterfly stands out in a crowd with its unique coloring and pattern.
Another defense of the Eastern Tiger Swallowtail is its Osmeterium, a horn-like organ that can be projected from the caterpillar’s head. Its dual functions are to mimic a snake’s forked tongue and to smell horrible to predators! Interestingly, to humans, the odor is strong but pleasant, like grass and pineapple!
#12. Spicebush Swallowtail Caterpillar
- Papilio troilus
Identifying Characteristics:
- The coloring is bright yellow-green with white-ringed black eyespots and smaller black dots along the back.
- The head of this species is larger than the tail-end.
- The primary host plants are spicebush and white sassafras.
Spicebush Swallowtail Caterpillars, like other caterpillars in southern Maine, are excellent at mimicry, both as larva and adults.
As adult butterflies, their coloring is similar to Pipevine Swallowtails, a similar species that has a bitter, foul taste. However, the truly remarkable mimicry is on display when this insect is still a caterpillar.
Its coloring is bright green, and its head is enlarged. On top, it has two large, round spots that look just like eyes, and it also has a forked red organ called an osmeterium that can be unfurled. All of these together make the caterpillar look like a fearsome green snake, especially to birds looking for a meal. Most potential predators steer clear!
As you might have guessed from its name this species prefers spicebush as its host plant. If you include spicebush in your garden, be sure it’s native to your area. You may be rewarded with a sighting of this wonderfully strange caterpillar or the beautiful adult butterfly!
#13. Cecropia Moth Caterpillar
-
Hyalophora cecropia
Identifying Characteristics:
- The coloring of this species changes with each instar growth. Most commonly seen in late instar; green with yellow, blue, and red bumps topped with black spikes.
- It has a large, fleshy body and very obvious leg appendages.
- Cecropia Caterpillars prefer birch, cherry, and maple trees for host plants.
Cecropia Caterpillars look more like aliens than anything!
Their bulbous bodies and multicolored, spiked nodules truly look like something from a sci-fi movie.
Look for Cecropia Caterpillars on maple, birch, and apple trees during late spring. They remain in their caterpillar stage for about two weeks before encasing themselves in their chrysalis for winter.
This species is one of many caterpillars in Maine called a “silkworm”. The name refers to the silk cocoon they spin around their chrysalis in preparation to become a moth. The cocoons are brown and cling to the side of host plants, and look like dead leaves.
As strange as Cecropia Caterpillars look, it’s nothing compared to the adult Cecropia Moth. Not only is the pattern and coloring beautiful, but this moth is also ENORMOUS! In fact, it’s the largest moth in North America!
#14. Monkey Slug
- Phobetron pithecium
Identifying Characteristics:
- Coloring is tan to brown with a lighter underside.
- Seven pairs of projections stick out from the sides of the flattened body.
- Monkey Slugs will use any woody-stemmed plant or tree as a host.
You shouldn’t have any trouble recognizing a Monkey Slug Caterpillar!
Its body shape is unique among caterpillars in Maine. In fact, with its fourteen leg-like projections covered in dense hair, you might even think you’ve found a particularly hairy spider instead of a caterpillar!
Monkey Slugs look pretty intimidating. Despite their tough appearance, their venom isn’t potent and usually only produces a mild rash. Individuals are solitary, so it’s unusual to find more than one. Their most common hosts are grove and orchard trees like apple and chestnut.
Look for Monkey Slugs during late summer, when they are most active and preparing to form their chrysalis. Their adult form, the Hag Moth, won’t be active until the following spring.
#15. Io Caterpillar
- Automeris io
Identifying Characteristics:
- The coloring is green with two stripes along each side, one red and one white.
- Tufts of short green spines cover the body, with patches of light green showing through.
- Io Caterpillars use hackberry and willow trees as host plants.
Io Caterpillars are highly venomous, and their sting is excruciating!
Fortunately, the sting is rarely severe enough to seek medical attention. Instead, most experts recommend removing the spines with scotch tape, then applying ice to the sting. Over-the-counter antihistamines and pain relievers can also help.
Of course, the best way to stay safe is to avoid touching Io Caterpillars. Since they’re so recognizable, this should be pretty easy!
Their tufts of green spines are distinctive and hard to miss against darker green leaves or brown bark. The red and white stripes on the sides are also helpful – they clearly say, “Stay back, I’m dangerous!”
If you know you’re going to be gardening or doing yard work in an area with Io Moths or their caterpillars, it’s a good idea to wear a hat and gloves. That way, if you happen to brush against one, you won’t have to worry about exposed skin!
Adult Io Moths are just as distinctive as their larva – if not more so! They have a beautiful pattern with large, prominent eyespots. There are two color morphs:
#16. Common Buckeye
-
Junonia coenia
- Caterpillars are dark brown to black with stripes along the back and sides and spines around the entire body.
Common Buckeye caterpillars in Maine are found in open spaces like pastures, old fields, and roadsides.
Although the butterflies are hard to approach and wary of predators, they fly low to the ground and will often perch long enough for you to snap a photo.
In the southern U.S., Common Buckeyes don’t have a specific mating season. Because the weather stays warm, they can continually reproduce.
Common Buckeyes in northern states migrate south for the winter and return in the spring for mating. These northern individuals can produce two to four generations each season!
#17. Large Yellow Underwing
- Noctua pronuba
You’re most likely to find these caterpillars in Maine in open or shrubby areas, but they are habitat generalists that can adapt to various conditions. For example, they’re happy in urban and suburban areas, fields, agricultural areas, yards, and parks.
The adult moths are mostly nocturnal and are attracted to outdoor lights. You may occasionally spot large groups of them around bright lights.
Large Yellow Underwings might not have the most creative name, but it’s certainly accurate! At rest, their brown forewings usually cover their brightly colored hindwings, but you’ll see a flash of color when they take off! This flash helps to confuse and startle would-be predators.
Large Yellow Underwings have a longer lifespan than many other moth species. In captivity, males live an average of 55 days, and females live about 75 days. Despite their long lifespan, they only have one new generation per year.
#18. Painted Lady
- Vanessa cardui
- The caterpillars’ coloring is variable, ranging from greenish-yellow to charcoal. Most have light-colored spots.
Look for Painted Lady caterpillars in Maine in open areas that are quiet and undisturbed, like roadsides, pastures, and gardens.
The population of Painted Lady’s can drastically differ from year to year. It’s common for them not to be seen for years in some places, then suddenly show up in significant numbers.
The Painted Lady is the only butterfly that mates year-round! Because of its constant migration pattern, it spends its entire life in suitable areas for its eggs to hatch.
#19. Red Admiral
- Vanessa atalanta
- The caterpillars are pinkish-gray to charcoal with white spots. They have spines along the back that resemble hairs.
Look for this caterpillar in Maine near the edge of forests in moist habitats.
Red Admiral Butterflies have a unique favorite food – they love fermented fruit! If you’d like to attract them, try placing overripe cut fruit in a sunny spot in your yard.
Red Admirals are migratory butterflies. They fly south toward warmer climates in winter and then move north again in late spring when food is more plentiful.
If you’re looking for a butterfly that’s easy to observe, you’re in luck! Red Admirals are very calm and easy to approach and frequently land on humans!
- RELATED: How to Attract Butterflies: 17 Tips!
#20. Pearl Crescent
- Phyciodes tharos
- Caterpillars are dark brown with cream stripes and spines all over their bodies.
The Pearl Crescent caterpillar’s preferred host plant is the Aster. Any flowering plants in your yard will attract this beautiful butterfly, but for best results, try to find one native to your area.
Look for Pearl Crescent butterflies in Maine near moist ground.
They prefer open, sunny habitats, but many locations suit their needs, including forest edges, fields, meadows, and gardens.
When the caterpillars grow into butterflies, they will feed on the nectar of the Asters as well!
#21. Rosy Maple Moth
- Dryocampa rubicunda
Rosy Maple Moths are undoubtedly the cutest caterpillars in Maine!
Even those uninterested in insects will love them. They’re common and fairly easy to find, too. These bright caterpillars spend time in deciduous forests and suburban and urban areas.
In northern areas, you’ll see Rosy Maple Moths from May to August, while in the south, you may spot them from April to September. Depending on their location, they may have one to three generations per year.
As their name suggests, Rosy Maple Moth caterpillars primarily feed on maple trees. They are especially fond of red, silver, and sugar maples. The coloration of the adult moths helps them blend in with maple seed cases as they reproduce and lay eggs.
After about a month, when the caterpillars are fully mature, they crawl down the tree and burrow into shallow underground chambers to pupate. Adults may emerge in as little as two weeks, but the pupae will overwinter in colder weather, and the adult moths emerge in the spring.
#22. Hickory Tussock Moth
- Lophocampa caryae
Interestingly, adult Hickory Tussock Moths don’t eat.
The adult moths don’t even have mouths! As caterpillars, they eat foliage from trees, but once they turn into moths, they spend all their time on mating and reproduction.
Female Hickory Tussock Moths lay batches of more than 100 eggs on the undersides of leaves in May or June. When these eggs hatch in Maine, the young caterpillars often remain in the same area for a while. You may see large groups of young caterpillars and some localized defoliation. Don’t worry, though; Hickory Tussock Moth caterpillars are a native species controlled by songbirds and other predators.
In the fall, they find a protected spot and spin a cocoon from plant debris and their own hairs. Like the caterpillars, the cocoons may irritate the skin, so it’s best to leave them where they are. In the spring, they emerge from their cocoons as moths.
#23. American Copper
-
Lycaena phlaeas
- Caterpillars are light green and sometimes have a pinkish tint along their sides. They’re covered with fine, downy hairs.
American Coppers can withstand many different climates, from the long, cold winters of the far north to humid, hot weather near the equator. American Copper butterflies are ordinarily active from June to September, but this season is longer in warmer areas.
To attract this caterpillar to your garden, try planting hawkweed or butterfly weed – these are the adults’ favorites for nectar.
#24. Spotted Tussock Moth
- Lophocampa maculata
Spotted Tussock Moths are in the tiger moth family, named for their patterns of alternating dark and light colors. These moths and their caterpillars are what’s known as polymorphic, meaning that they come in many color variations.
You’ll most likely find Spotted Tussock Moth caterpillars in Maine in deciduous forests. Researchers have found that Spotted Tussock Moths have a regional taste for cuisine, just like people! Caterpillars from certain regions often prefer specific tree species.
After about two months of feeding, the caterpillars pupate. They spin brown silk cocoons attached to leaves where they will overwinter, emerging as adults the following spring.
#25. Mourning Cloak
- Nymphalis Antiopa
- Caterpillars are black with white specks and a row of red spots on the back.
Mourning Cloak caterpillars are most often found near deciduous forests. However, their habitat includes many developed areas like suburban yards, parks, and golf courses.
You might have a hard time finding this caterpillar in Maine.
Even though it’s fairly widespread, its preference for cold weather and solitary habits make it hard to spot, even for avid butterfly enthusiasts!
Mourning Cloaks are often the first butterflies to become active in the spring! In fact, some adults are even active through winter on warm days when snow is still on the ground.
They’re also one of the longest-lived butterflies, with some individuals living up to ten months!
#26. Forest Tent Caterpillar Moth
- Malacosoma disstria
Forest Tent Caterpillar Moth populations fluctuate in cycles, so you may go years without seeing any and then see lots of them in one season. Their populations reach outbreak proportions every 6-16 years.
Adult Forest Tent Caterpillar Moths are active in July, don’t feed, and live for ten days. Especially in outbreak years, you might spot large groups clustered around outdoor lights.
Unlike other tent caterpillars, Forest Tent Caterpillars don’t spin true tents. Instead, they spin silk mats on the tree’s trunk or branches where they rest when they’re not feeding.
Do you need more help identifying caterpillars in Maine?
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Which of these caterpillars have you seen in Maine?
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