15 Weird (but COMMON) Caterpillars in New Brunswick (2024)

What kinds of caterpillars can you find in New Brunswick?

Kinds of Caterpillars in New Brunswick

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 New Brunswick!

Since it would be impossible to list them all in one article, I chose the 15 most interesting and common ones to share with you. 🙂


#1. Monarch Caterpillar

  • Danaus plexippus

Types of Caterpillars that live in New Brunswick

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 New Brunswick!

Common New Brunswick Caterpillars

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. 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! 🙂


#3. 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 New Brunswick!

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.


#4. 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 New Brunswick!

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!


#5. Hornworms

  • Manduca sexta – Tobacco Hornworm
  • Manduca quinquemaculata – Tomato Hornworm

Identifying Characteristics:

  • These two species have nearly identical coloring: bright green with tiny white lines and black dots.
  • There’s a thin, filament-like “horn” on the rear end.
  • Hornworms grow up to 3.5 inches in length before metamorphosis.

Tobacco and Tomato Hornworms are so similar that they’re often mistaken for one another! The easiest way to tell them apart is by the color of their horns. Tobacco Hornworms have a red horn, and Tomato Hornworms have a green or black horn. While the adult moths they grow into aren’t quite as similar, they do have the same coloring.

Hornworms are considered one of the most destructive caterpillars in New Brunswick.

They specialize in eating tobacco, tomato, and other similar plants and regularly cause problems for farms and growers who don’t use pesticides. However, relocating or killing the caterpillars can be enough for many home gardeners to deter any more from eating your plants.

One particularly disgusting enemy of the hornworm is Cotesia congregata. It’s a parasitoid wasp that attacks the caterpillar with venom and then lays its eggs INSIDE the living body. As the caterpillar matures, so do the wasp eggs, slowly feeding on the hornworm until it dies and the wasps hatch. Gross!


#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 New Brunswick 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. 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!


#10. 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 New Brunswick 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!


#11. Painted Lady

  • Vanessa cardui
Vanessa cardui. (2023, August 10). In Wikipedia.
  • The caterpillars’ coloring is variable, ranging from greenish-yellow to charcoal. Most have light-colored spots.

Look for Painted Lady caterpillars in New Brunswick 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.


#12. 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 New Brunswick 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!


#13. Rosy Maple Moth

  • Dryocampa rubicunda

Rosy Maple Moths are undoubtedly the cutest caterpillars in New Brunswick!

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.


#14. 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 New Brunswick 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.


#15. 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 New Brunswick.

Even though it’s fairly widespread, its preference for cold weather and solitary habits make it hard to spot, even for avid butterfly enthusiasts!butterflies in the united states

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!


Do you need more help identifying caterpillars in New Brunswick?

Here are some recommended books on Amazon!


Which of these caterpillars have you seen in New Brunswick?

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