World’s Top 15 Poisonous Caterpillars

Poisonous Caterpillars: When everything is painted green in the spring, and the forests and glades are full of life, we may be eagerly anticipating the blooming season. Flowers emit a fragrant fragrance that attracts colorful butterflies to meadows and gardens. But, butterflies cannot develop unless they go through the caterpillar stage.

In a sense, those worm-like creatures are butterfly children. They exist to feed, grow, create cocoons, and provide enough energy for a future butterfly. Caterpillars are not typically the most popular insects.

They destroy plants by eating leaves – after all. Some caterpillars, on the other hand, are beneficial. For those who try to touch or eat them, they might be quite dangerous.

Caterpillars annoy gardeners since they harm fruit crops and vegetation, but other animals enjoy them. Many predators pose a threat to caterpillars. To stay out of the jaws of predators, they use a variety of defense tactics!

Their coloring, for example, may allow them to blend in with their surroundings bycamouflaging. Colonies develop when different species coexist. However, a third, considerably more perilous survival technique will be discussed now.

Several caterpillars develop chemical warfare – they become poisonous. Moreover, some have developed poisons that can kill a human.

How do caterpillars become poisonous?

There are several methods the insects can use to become poisonous.

Some caterpillars feed on poisonous plants like milkweed and store poison inside; others leak acids.
However, the most dangerous caterpillars have developed detachable weapons containing potential chemical warfare.
The latter group is quite numerous, and one can find caterpillars with stinging hairs in the Americas, Europe, and Australia.

Poisonous Caterpillar vs. Venomous Caterpillar

Because of the poisonous chemical it transports, a poisonous caterpillar might harm you if you touch, breathe, or eat it. A venomous caterpillar, on the other hand, injects a toxin or poison into a sting with its stinger. As a result, we have highlighted venomous vs. non-venomous caterpillars in the list below. It’s a poisonous species, isn’t it?

Top 15 Poisonous Caterpillars

Caterpillars that are poisonous can be divided into a variety of groups. Except for perhaps the poles, they can be found almost anywhere on the planet. In this regard, North and South America are particularly fortunate (or unlucky): poisonous caterpillars may be found in almost every country in the world, and those in South America are especially harmful.

Buck Moth Caterpillar (Venomous)

The first poisonous caterpillar on our list is the Buck moth caterpillar. These caterpillars can be seen in most states of the Southeastern US.

These harmful caterpillars have black bodies with distinct white spots.
There is a light form of the species that has a body with a greenish coloring and more prominent spots that look like starfish.
The head and limbs called prolegs are red.
Multiple, thin, branching spines cover the body.
These venomous caterpillars usually come out around July, and the adult moths fly out in autumn.
These most poisonous caterpillars prefer to eat oak leaves but can also dine on willow, hazelnut, cherry, rose, and grasses.
The breakable spines on the caterpillar’s body carry a poison that can cause different reactions, from simple rash or swelling to severe shock.
This species is a part of the giant silkworm moths family, which also contains big, beautiful butterflies beloved by collectors.

Saddleback Caterpillar (Poisonous)

These unique, slug-like poisonous caterpillars can be found in the Eastern United States.

Saddleback caterpillar has a small, stocky body and resembles a slug.
Primary body color of this poisonous caterpillar is brown, and there is a distinct, bright green marking in the middle of the body, with an oval-shaped reddish mark in the middle that resembles a saddle.
You can quickly notice two stocky, thick thorns on both head and tail covered with spines.
Saddlebacks hatch from the eggs in spring and late winter (February-March), as they need around 5 months to grow and turn into a butterfly entirely;
These deadly caterpillars are universal feeders and can eat leaves of multiple types of trees, including maple, oak, palms, and chestnuts.
This venomous caterpillar has a potent poison that destroys blood cells. Even a small prick from the poisonous spine can cause asthma, stomachache, and bleeding.
When attacked, the saddleback tries to shorten its stocky body as much as possible, putting the blackthorns with spine forward.
The moth of this caterpillar is wholly unremarkable and is painted in mottled brown.

Monkey Slug Caterpillar/Hag Moth Caterpillar (Poisonous)

The butterflies of this species usually reside in the Eastern States of the USA.

The so-called “monkey caterpillar” has a short, stocky body with nine pairs of bendable “arms” covered in brown, thin hair.
This poisonous caterpillar usually feeds on the underside of the leaves and relies on suction cups to hold on.
These slug-like critters usually hatch in the spring.
Unlike real monkeys, these creatures are not picky about food and can be found on leaves of different trees, from oak and elm to apple and cherry.
The poison of the hair is mild and causes allergic reactions only in particularly sensitive people.
While the caterpillar itself is called “monkey slug, the adult moth is named “hag moth,” though it is instead an ordinary-looking insect with yellowish wings that has nothing nightmarish about its appearance.

Hickory Tussock Caterpillar (Poisonous)

The Hickory tussock caterpillar is the second poisonous caterpillar on our list. Southern Ontario, Canada is home to these species.

The body of this caterpillar is painted in black and white: The primary color of the body is white, with thin hair on the sides. There are connected black markings in the middle of the back.
The front and the rear of the caterpillar’s body are covered with long, black hair that contains poison.
A prick from the poisonous hair results in a rash or a swelling similar to poison ivy.
People sensitive to the tussock caterpillar poison may develop severe allergic reactions or feel nauseous.
The black & white caterpillars are specific feeders and prefer hickory, walnut, elm, and oak leaves.
It is better to be wary of these black and white fuzzy caterpillars from July to September when they actively roam and feed.

Southern Flannel Moth Caterpillar or Puss Caterpillar (Poisonous)

In the Southern states, including New Jersey, Arkansas, Florida, and Texas, the puss caterpillar is common.

The young caterpillars look ordinary – small, thin, yellow, and covered with hairs sticking from the sides.
These Florida caterpillars, at the last stages of growth, have a slug-like tiny body covered with many orange or bright yellow hairs that resemble fur.
The poison of the mature caterpillar is highly dangerous and can destroy blood cells.
People who touch the animal usually feel the burning pain immediately, followed by a rash that looks like an imprint of the spines.
Then, the people may develop bleeding, difficulty breathing, and other dangerous symptoms.
There were reports when schools were closed in Texas due to the abundance of puss caterpillars. These insects prefer oak and citrus trees that often grow near schools and kindergartens, and children often try to grab them.

Spiny Oak Slug Moth Caterpillar (Venomous)

The poisonous caterpillars continue with the Spiny Oat Slug Moth Caterpillars. They may be found from Virginia to the northern reaches of Ontario, Canada.

These stinging caterpillars can appear twice a year in warmer areas and only once a year in spring in colder ones.
This caterpillar is more conventional. The body can be light green, yellow, reddish, or orange.
This venomous yellow caterpillar feeds on oak leaves exclusively.
The body of the spiny oak slug moth is covered with dense branching horn-like structures with tiny short spines on them, resembling holly trees.
The spine’s poison causes mild allergies.

Io Moth Caterpillar (Venomous)

Cape Cod and Massachusetts, as well as the Gulf States and New England, are home to Io moth butterflies and their caterpillars.

As they grow, the caterpillars change their color from reddish brown with black spines to light green with reddish-white stripes.
The spines of Io moth caterpillar are arranged in distinct “bouquets“.
This stinging caterpillar is not a picky eater and feeds on many types of trees – maples, cherries, birches, and even cranberry and gooseberry plants.
The spines arranged in “bunches” are mildly poisonous. Usually, cause allergic reactions.
The moth of this species is usually active in the afternoon and evening and has distinct “eyes” on the lower wings.

White Flannel Moth Caterpillar (Poisonous)

This poisonous caterpillar can be found in Louisiana, Mississippi, Alabama, and Tennessee. It is a relative of the southern flannel moth caterpillar.

Unlike its more famous relative, the white flannel moth caterpillar has a dark-colored, small body with round, yellow-colored patches.
There are puffs of stinging black hair on the back.
The head and tail of the caterpillar are orange, in contrast to the rest of the body.
White flannel moth caterpillar possess stinging hair that causes pain, sometimes allergy, and swelling.
Another distinct feature of the white flannel moth caterpillar is the presence of a chain made of natural black triangle markings between the bright yellow spots.
This poisonous yellow caterpillar prefers hackberry, black locust, and redbud.

Stinging Rose Caterpillar (Venomous)

Several states west of Texas and Oklahoma, such as Florida, New York, Philadelphia, and Illinois, have populations of this unusual poisonous caterpillar.

The appearance of the stinging rose is very striking: the caterpillar has a bright yellow or orange body with a signature purple stripe running along the back. There are also reddish lines on either side of the caterpillar’s body.
The poison is contained in the stocky yellow horn-like structures with smaller and thinner spines that cover the body.
You risk encountering these spines almost everywhere, as this stinging caterpillar can be found on rose bushes, maples, oaks, poplars, dogwood, and hickory.
The poison mainly causes allergic reactions, which can be severe in sensitive people and quite mild for others.

American Dagger Caterpillar (Poisonous)

This species is truly American – it can be found throughout Eastern North America.

The body of the American dagger moth caterpillar is short, covered with thin, long green hair.
Thin, long black spines protrude among the fur-like hair, forming a whole bunch on the rear end.
The black thick spine-like hair is the source of the poison that can cause a painful rash.
The spiky green caterpillar feeds on most common forest trees, such as oak, ash, and elm.
Is American dagger moth caterpillar poisonous to humans? Of course, it is. Some people can find them on the ground – do NOT pick them up without gloves!

Smeared Dagger Moth (Poisonous)

Another member of the dagger moth family, this poisonous caterpillar, also lives in Eastern North America.

The caterpillar’s body is black with bright yellow stripes on the sides.
Smeared dagger moth caterpillar also has stinging hair that causes severe pain, allergy, and swelling.
The back of the caterpillar is adorned with bunches of thin, white bristles, reddish at the base.
The Smeared dagger moth caterpillar can feed on anything from grasses to fruit trees.

Laurelcherry Smoky Moth (Poisonous)

This mildly poisonous caterpillar lives in Florida.

This species prefers Carolina laurelcherry to anything else.
This caterpillar’s short and stocky body is transparent yellow on the sides, with intermittent black stripes.
The danger comes from the small, short, yellowish hair that covers the body.
The hair stings – the victim first feels pain, then a rash develops on the skin, followed by blisters.
This caterpillar also has a small hood that can hide his head when necessary.

Variable Oakleaf Caterpillar (Poisonous)

This poisonous caterpillar is another resident of Eastern North America.

As the name suggests, the caterpillar is almost exclusive to oaks.
If you wish to meet the species – wait for July or August.
It has earned the name “variable” because it can have different markings on its long, lanky body.
The only universal feature is the distinct reddish stripe on the back.
Even if there are different variations, the main colors the caterpillar wears are red and green.
Instead of poisonous spines, this caterpillar produces formic acid that stings and can cause allergy.

In addition, we’d like to introduce you to two butterfly and moth species found outside of the United States.

Pine Processionary Caterpillar (Poisonous)

The next poisonous caterpillar lives in Southern Europe.

These caterpillars of this species are social: they form colonies that travel together from tree to tree.
The caterpillar’s body is colored green with yellow stripes and is covered with thin, whitish spines.
This caterpillar feeds exclusively on pine needles; each colony settles on a pine branch and makes a nest of silk threads.
The spines can cause only a mild allergy in humans, but they are dangerous for pets, especially dogs.
Tourists visiting France and Spain are advised to keep their dogs from the processions of caterpillars and to avoid standing under pines in summer, especially if there are caterpillar nests.

Giant Silkworm Moth Caterpillar (Poisonous)

The last poisonous giant silkworm moth caterpillar is a Brazilian citizen and prefers rainforests.

The color pattern of the giant silkworm caterpillar is not particularly remarkable – mostly brown and green, with a striped pattern.
The whole body of the caterpillar is covered with thin white spines with multiple branches. The endings of the branches are colored black.
The venom of this caterpillar can prevent the blood from clotting, causing bleeding and destruction of the body from within.
The medics around the world actively study this venom because it can help treat some heart diseases because of its ability to dissolve blood clots.
These caterpillars are also guardians: the trees where the giant silkworms reside are not damaged by monkeys or other animals. This way, the trees get high-class protection for the price of the few leaves.

Does a caterpillar being poisonous really help it?

As you can see, there are a lot of poisonous caterpillars. Nonetheless, it does not mean the poison shields them completely.

The birds that desperately need protein that the caterpillars can provide find their own ways.
Some eat caterpillars when they are very young and have weak poison.
Others develop a resistance to a particular poison that the caterpillars use.
Of course, giant silkworms are the exception – no known animal can stand up to them.

Finally, if you come across a bright-colored, fluffy caterpillar with horns or spines that make you uneasy, stay away. Use protection if you must. It’s preferable to be on the safe side when several species purport to be poisonous.