Top 14 Poisonous Caterpillars in the World

Poisonous Caterpillars

Caterpillars are indeed an art of nature. With those vibrant colors & breathtaking designs on their body, they are nothing short of anything other than adorable critters.

For most people, caterpillars are harmless critters that quietly chew on the leaves, waiting to transform into winged creatures and take flight. But little do they know that most of these seemingly harmless caterpillars are ranked among the deadliest bugs on this planet.

Due to their cuteness and fuzzy nature, caterpillars are often perceived to be defenseless critters. But you didn’t think they are born without any means to defend themselves, right? Because if they were harmless as they look, they would have been an easy snack to most predators.

But how often do you see a caterpillar being attacked by a predator?

Most predators take care to keep a safe distance from these caterpillars. They do so because most of these caterpillars are poisonous!

Not just to the predators, these poisonous caterpillars are a threat to human beings as well! Though they aren’t as dangerous as a venomous snake, caterpillars can still cause serious complications to human beings.

In this article, we will discuss in detail about the 14 poisonous caterpillars that can kill you. The 14 poisonous caterpillars that we are going to discuss are:

  1. Puss Caterpillar
  2. Saddleback Caterpillar
  3. Pipevine Swallowtail Caterpillar
  4. Io Moth Caterpillar
  5. Bag Shelter Caterpillar
  6. Monarch Caterpillars
  7. Hag Moth Caterpillar
  8. Hickory Tussock Caterpillar
  9. Pine Processionary Caterpillar
  10. Cinnabar Moth Caterpillar
  11. Stinging Rose Caterpillar
  12. Lonomia Obliqua
  13. Spotted Oleander Caterpillars
  14. The Buck Moth Caterpillars


Before we go into knowing more about these caterpillars, we must understand more about the caterpillars.


How do caterpillars become poisonous?

Poisonous Caterpillars

A caterpillar is the larval stage of a butterfly or a moth. It is interesting to note that these slow-moving critters that may appear to be defenseless to most have developed some interesting ways to protect themselves. Among all the techniques, our interest lies in those caterpillars that are venomous.

Caterpillars spend most of the time munching on leaves. Most of these caterpillars have devised a mechanism to store the toxins from the leaves of the plants they eat in glands that are present under their skin.

If you closely observe a caterpillar, you can see the pointed spines that lay hidden under their hairs. These spines are hollow and are connected to the glands beneath their skin that produce poison.

When an animal comes in contact with these caterpillars, they are stuck with the spines, and the venom is injected in. Though most of these caterpillar’s venom isn’t toxic, they are adequate to keep the predators away.

Now let us have a look at some of the venomous caterpillars out there!


14 Venomous Caterpillars That Are Dangerous


Puss Caterpillars – The caterpillar whose sting can felt in the bones

Puss caterpillars are the larval stage of the southern flannel moth, an attractive small moth that is commonly seen in the US. These caterpillars are known to be the most venomous caterpillar in the USA.

Puss caterpillars are known for their soft hairs resembling a cuddly house cat. Owing to their cute looks, these caterpillars are not considered to be a threat by most people.

But don’t be deceived by their looks, these caterpillars hide sharp spines between their hairs and a poison secreting gland under their skin. A sting from these caterpillars can be ten times more powerful than a bee sting.

Those who were stung by these caterpillars say that they could feel the pain in their bones. To date, there haven’t been any reported cases of serious injuries or loss of life caused by these caterpillars!



Saddleback Caterpillar – The colorful yet deadly one

Saddleback Caterpillar

The saddleback caterpillars are the larval stage of the fuzzy dark brown moth.

These caterpillars are known for their vibrant green color and the purple dot on their back, resembling a saddle. Owing to their irresistible cuteness and bright coloration, they are not considered to be a threat.

But don’t be deceived by their cute looks, the saddlebacks can land a deadly sting that can cause burning pain and burning sensation that can last for several hours.

The pain and swelling from their sting can be more than that of a bee sting. What makes the saddlebacks deadly is that their poison is found to be allergic to most people, especially those with allergic reactions or sensitivity to a bee sting.

So if you were to encounter a saddleback caterpillar, make sure that you don’t touch them!


Pipevine Swallowtail Caterpillar

Poisonous Pipevine Swallowtail Caterpillar

The pipevine swallowtail is a swallowtail butterfly that is commonly found in the central and northern America known for their iridescent-blue hindwings.

Its caterpillar is known for its unique black color, which is a very different coloration when considering the coloration of the other poisonous caterpillars.

The pipeline swallowtail mainly consumes the leaves of the toxic plants Aristolochia, also known as the pipevine or birthwort.

The leaves of this plant are found to have a high concentration of the lethal toxin aristolochic acid. Aristolochic acid toxicity can cause renal failure in humans and other animals.

Well, the risk only arises if you were to consume them, which is highly unlikely.


Io Moth Caterpillar

Io Moth Caterpillar

Io moths are one among the easily recognizable moths known for its distinctive eyespots on its hind wings. Unlike the adult moths, the caterpillars are known for their pale green color with a lateral stripe of pink and creamy white down each side.

The entire body of this caterpillar is covered with venomous spines that can land a deadly sting. These pointed spines on its body are connected to the poison gland under their skin like the other caterpillars.

Once these spines penetrate the skin of an unfortunate animal, its tip breaks off and eventually injects the venom on to its body. These broken chitinous particles that are left in the skin causes inflammation too.


Bag Shelter Caterpillar

Poisonous Bag Shelter Caterpillar

Bag shelter caterpillars are the larvae of the Bag-shelter Moths that are mainly found in Australia. These caterpillars are known best for being hairy and processionary.

During autumn and summer, these caterpillars follow each other head to tail forming long chains, which is an interesting sight to behold.

Though these bag-shaped caterpillars look harmless, they are best left alone. Even an accidental contact with the hair or spines of these caterpillars can cause a severe allergic reaction on the skin.

Owing to the severe itching and allergic reaction caused due to these caterpillars, they are commonly called “itchy grubs” in some parts of Australia.


Monarch Caterpillars

Monarch Caterpillars

Monarch butterflies are stunning.

With their bright orange wings, a black border and white spots make them probably the beautiful among all the butterflies. But these stunning butterflies are known for the mass migration they do during the winter.

What makes it even interesting is that these butterflies with an average lifespan of only eight weeks do not make the return trip after migration.

The larvae of the monarch butterflies are born on the leaves of the milkweed plants. These larvae eat the leaves of these plants and absorb the toxins in the leaves.

It is important to note that these caterpillars are not poisonous to human beings but are poisonous to other predators. The toxins in the caterpillar will not kill the animal, but it is powerful enough to make them sick!


Hag Moth Caterpillars

Poisonous Hag Moth Caterpillars

The hag moth caterpillars are known for their bizarre alien-like looks. These hairy caterpillars have nine pairs of fleshy appendages on their sides, most of which are long and twisted.

Due to the look of these appendages, most people believe these appendages are used for locomotion. But in reality, it isn’t used for locomotion. If you have a closer look at the caterpillar, you can see that their real legs are present underneath their body.

Though the hag moth caterpillar may look cute and virtually harmless, don’t be deceived by their looks. In between those short and brown hairs covering their body, some are connected to the toxin glands under their skin.

Even an accidental contact with those hollow hairs can cause burning and itching sensation along with redness and inflammation, similar to a bee sting.


Hickory Tussock Caterpillar

Poisonous Hickory Tussock Caterpillar

The Hickory Tussock caterpillar is widely known for its iconic black and white appearance. These caterpillars are found to be both allergic and poisonous.

It has been identified that the black hairs found on these caterpillars are hollow and are connected to the gland producing poison under their skin.

It is important to note that some hairs of the Hickory Tussock caterpillars have barbs that can get stuck in the skin. These barbs sometimes break, leaving behind the small pieces on your skin, causing an allergic reaction.


Pine Processionary Caterpillar

Poisonous Pine Processionary Caterpillar

The pine processionary caterpillar is the larval stage of a moth that is commonly found in the pine trees. These caterpillars are known as the most destructive pest species to the pine and cedar trees in Central Asia & North African forests.

It is interesting to note that these caterpillars form long chains when they migrate from treetops to loose soil to pupate.

Like most caterpillars, the pine processionary caterpillars also look defenseless but don’t be deceived by their appearance. Towards the end of the larval development, the hairs on its body can cause severe skin rashes and, at the time, infection in the eyes too.

Similarly, those caterpillars that are nearing the end of the larval stage can penetrate its hair into the skin of its predators and then breaking it off, leading to severe allergic reactions.


Cinnabar Moth Caterpillar

Cinnabar Moth Caterpillar

Cinnabar moths are brightly colored caterpillars that are known for the red patches on its black wings. The cinnabar moths lay their eggs on the leaves of ragworts and groundsels, and once the eggs hatch and reach the larval stage, they begin consuming these leaves.

The caterpillars of the cinnabar moths are heavy eaters, and they encounter a lack of food at times. It is interesting to note that once the food becomes scarce, these caterpillars show cannibalistic nature.

The caterpillars absorb the toxins and alkaloid substances present in the leaves of these plants and assimilate them.

The cinnabar moth caterpillars have a pale orange color and black stripes on its body, making them irresistibly cute. But make sure that you don’t touch them because they can cause serious allergic reactions on your skin!


Stinging Rose Caterpillar

Stinging Rose Caterpillar

The stinging rose caterpillars are the soft and cuddly caterpillars of the handsome green and pale brown moths. Owing to their cuddly look, they may appear to be innocuous but don’t be deceived by their looks.

Like all other venomous caterpillars, they have hollow spines on their body protruding outwards that is connected to a poison secreting gland underneath their skin.

Any encounter with these seemingly innocuous caterpillars can cause allergic reactions, especially on children.

Common symptoms include burning sensation followed by an itching sensation, and these can eventually develop into skin rashes if left untreated.



Lonomia Obliqua Caterpillar – The venomous caterpillar that can kill you!

Lonomia Obliqua Caterpillar

The Lonomia Obliqua caterpillar is the larval stage of the silkworm moth mainly found in South America. Though most caterpillars have venom, the most they can cause is a burning sensation or a skin rash.

Unlike its counterparts, the venom of the Lonomia Obliqua caterpillar is extremely deadly that there have been many reported cases of death due to its venom.

It is important to note that the venom of this caterpillar, once injected, can cause severe blood clots throughout the body, causing internal hemorrhages and eventually death.

For the venom to cause such serious injuries, it has to be injected in higher doses. Which means that the victim has to be stung at least 50 times for fatality.


Spotted Oleander Caterpillar

Poisonous Spotted Oleander Caterpillar

As the name suggests, the spotted oleander caterpillars are commonly found on the leaves of the oleander shrubs. These caterpillars have a bright orange body covered in tufts of long black hairs.

During the larval stage, they mainly feed on the leaves of the oleander and takes up the toxin on the leaves.

Owing to the high levels of toxin in their body, most birds and the other common predators do not feed on them. But yeah, these caterpillars do not pose any serious threat to humans other than skin rashes and inflammation.



Buck Moth Caterpillar

Poisonous Buck Moth Caterpillar

The buck moth caterpillars are commonly seen in the southern states of the US. These caterpillars have a black body and iconic white spots on them, resembling the color of a starfish.

Similar to the other poisonous caterpillars, the buck moth caterpillars also have urticating thin and branched spines on its body.

These breakable spines are connected to the poison gland under their skin, and it can cause anything from simple rash or swelling to severe shock.



Now that we have discussed some of the poisonous caterpillars, it is important to understand that not all caterpillars pose any serious threats to human beings except the Lonomia Obliqua.

Most of these caterpillars use their venom as a deterrent against predators and do not have enough toxicity to kill humans.



How can you tell if a caterpillar is poisonous?

There isn’t a definite science behind properly identifying whether a caterpillar is poisonous or not. The best way to go about it is to follow the method of elimination.

Basically, all caterpillars with spines and hair are poisonous. It takes an expert to properly identify them, and it is best not to touch them. In case you want to remove them from someplace, use a small twig or a leaf to do the job.



What color are poisonous caterpillars?

color of poisonous caterpillar

There are about 20,000 identified species of caterpillars in the world, and only God knows how many more are there. Which means that there isn’t a specific color code for the poisonous caterpillars.

In general, the poisonous caterpillars all have bright and vibrant colors. The poisonous caterpillars, in general, are red, black, and yellow, with bright stripes on their body. These colors are more like an indication to stay away from them!


What is the most dangerous caterpillar?

The most dangerous caterpillar is the Lonomia Obliqua caterpillar owing to its deadly venom. These caterpillars are responsible for several deaths in a year, and it has earned them the name “Assassin Caterpillars”.

These caterpillars are found in the humid rain forests of Brazil, and they are quite difficult to spot as they can camouflage themselves excellently.

What makes these caterpillars extremely dangerous is the fact that they are commonly found in groups. This means that even a small accidental brush against them can lead to you coming in contact with a lot of spines.

The venom produced by these caterpillars interferes with the coagulation of blood. Even contact with a few of their spines can cause vomiting, internal bleeding, and the rupture of red blood cells.

If the venom is injected in higher doses, it can lead to massive hemorrhage and internal bleeding, which eventually leads to renal failure and death.


Are black fuzzy caterpillars poisonous?

No, the black fuzzy caterpillars aren’t poisonous, but they do sting. Their sting can trigger an allergic reaction on some people, but that’s pretty much everything.

That being said, you need to be extremely careful while handling them because it takes an expert to identify them properly.

Not all black caterpillars are safe to handle, which is why you need to be extremely careful while handling one.


Are caterpillars poisonous to dogs?

Are caterpillars poisonous to dogs

Yeah, caterpillars can be poisonous to dogs. A caterpillar, in general, has two types of hair or spines on their body. One is called the urticating hair, and the other is the stinging one, and these two work differently.

The urticating hairs are the non-venomous and itchy ones that can only cause an allergic reaction on the body.

These allergic reactions are triggered by our body due to the presence of a foreign object, and it heals within a short time. Considering the thick outer coat of a dog, chances of these skin allergies are very less.

But that isn’t the case with the stinging hairs. Dogs are extremely curious, and they would sniff or lick the caterpillar and come in contact with the stinging hairs.

These hairs are hollow and are connected to the poison secreting gland underneath the caterpillar’s skin. Once this venom is injected into the dog, it can cause excessive drooling, pawing due to discomfort, gastritis, esophagitis, difficulty in swallowing, tongue, lip, and oral irritation.

In case your dog shows any of these symptoms, you should take them to a vet at the earliest!


Are oleander caterpillars poisonous?

Yes, oleander caterpillars are poisonous. As the name suggests, these caterpillars are found on the leaves of the oleander shrubs, and they feed on its leaves.

The oleander leaves contain a toxin called glycosides, and these caterpillars absorb this toxin.

Because of the presence of glycosides, these caterpillars are poisonous to some birds and other predators. That being said, the poison of these caterpillars do not pose any serious threat to humans.


Are yellow caterpillars poisonous?

Some yellow caterpillars are poisonous, while some are not. For instance, the seemingly harmless and cute yellow-necked caterpillar is not poisonous while the yellow fuzzy caterpillars are.

As said earlier, it takes an expert to identify caterpillars properly.

If you are not sure about a caterpillar, it is best to stay away from them!


Are monarch caterpillars poisonous?

The monarch caterpillars are poisonous due to the presence of cardenolides they absorb from the milkweed plants. Though they are poisonous, they don’t pose any threat to humans except for their bad smell.


Are swallowtail caterpillars poisonous?

Not all swallowtail caterpillars are poisonous. For instance, the black swallowtail caterpillars are not poisonous, whereas the spicebush caterpillars are poisonous. So it is better to leave them on their own!

It is important to note that, irrespective of the species, all swallowtail caterpillars have a gland that secretes a foul-smelling and tasting chemical that keeps the predators away.


Are Luna moth caterpillar poisonous?

No, the Luna moth caterpillars are not poisonous, and because of this reason, they are preyed upon by many birds and bats. Though they lack poison like other caterpillars, they aren’t defenseless after all.

When threatened, these caterpillars regurgitate unpleasant fluids onto their attacker that keeps them safe.

Apart from this, they can camouflage well owing to their bright green color, which makes it difficult for the predators to spot them.


Poisonous Caterpillars in Ohio

  • Smaller Parasa Caterpillar
  • Saddleback Caterpillar
  • Crowned Slug Caterpillar
  • Hag Moth Caterpillar
  • Skiff Moth Caterpillar
  • White Flannel Moth Caterpillar
  • Black-Waved Flannel Moth Caterpillar
  • Lo Moth Caterpillar


Poisonous Caterpillars in Texas

  • Puss Moth Caterpillar
  • Black Swallowtail Caterpillar


Poisonous Caterpillars in Florida

  • Puss Caterpillar
  • Saddleback Caterpillar
  • Lo Moth Caterpillar
  • Hag Moth Caterpillar
  • Buck Moth Caterpillar
  • Spiny Oak-Slug Caterpillar
  • Flannel Moth Caterpillar


Poisonous Caterpillars in Alabama

  • Saddleback Caterpillar
  • Hag Moth Caterpillar
  • Stinging Rose Caterpillar
  • Spiny Oak Slug


Poisonous Caterpillars in Wisconsin

  • Puss Caterpillar
  • American Dagger Caterpillar