5 Types of Poisonous Caterpillars

Although they may look adorable and harmless, there are five types of poisonous caterpillars that you need to watch out for. Surprisingly, these toxic critters can be found in many parts of the country, so it’s important to know what to look for and how to protect yourself. 

Read on for more information on these dangerous insects!

How To Identify Poisonous Caterpillars

Poison VS Venom

Let’s start with the difference between poison and venom. To put it simply, if you ingest or absorb poison, it’s called poison. If you inject venom, it’s called venom. Pretty straightforward, right? But of course, there’s always a bit more to the story.

Let’s start with poison. This can come in many forms, but the one thing they all have in common is that they enter the body through some sort of contact. It could be skin contacts, like poison ivy or poison oak. It could be inhalation, like carbon monoxide poisoning.

Or it could be ingestion, like food poisoning. In any case, once the poison is in your body, it begins to wreak havoc. Symptoms can range from mild (rash, nausea) to severe ( organ failure, coma).

Venom, on the other hand, is injected directly into the bloodstream. This can happen via a sting (bee, wasp), a bite (snake, spider), or even a needle (drugs). The effects of venom are usually more immediate and more severe than those of poison because it doesn’t have to go through the digestive system to get into the bloodstream. 

So, how to tell if a caterpillar is dangerous?

One way to identify a poisonous caterpillar is by its color. Brightly colored caterpillars are more likely to be poisonous, as they use their bright colors as a warning sign to predators.

Another way to tell if a caterpillar is poisonous is by its appearance. If a caterpillar has spikes or bristles, it’s likely that it will sting if you touch it.

Finally, Caterpillars that emit a foul odor are also likely to be poisonous.

Not all caterpillars with poisonous characteristics are dangerous, and they do not sting like bees or wasps. Urticating hairs are also one of the most important features to look for. Urticating hairs are barbed or spiky structures that cover the surface of some caterpillars. 

When these hairs come into contact with human skin, they can cause irritation and discomfort. In severe cases, they can even lead to death. So, if you’re planning on picking up a caterpillar, it’s important to first make sure that it’s not going to hurt you.

While urticating hairs may seem like a daunting defense mechanism, keep in mind that not all caterpillars with these structures are dangerous. In fact, many of them are quite harmless! 

5 Types of Poisonous Caterpillars

Giant Silkworm Moth Caterpillar (Lonomia obliqua)

The giant silkworm moth caterpillar is one of the most poisonous caterpillar species around – and it’s not hard to see why. These brightly-colored creatures are covered in spikes that contain a high level of poison, making them a danger to both humans and animals. 

Although they’re usually found in southern Brazil, Uruguay, Paraguay, and Argentina, they have been known to turn up in other parts of the world from time to time.

These caterpillars grow to be about two inches (5 centimeters) long when fully grown, and their colors can range from brown to green. Their spikes also come in different sizes depending on the species. 

If you’re unlucky enough to be stung by one of these caterpillars, you can expect to experience a range of symptoms including fever, blurred vision, confusion, weakness, and loss of balance. 

In some cases, the poison can even be fatal. However, it’s worth noting that most reactions only occur after 20-100 stings – so unless you’re planning on cuddling up to a whole swarm of them, you should be fine.

Puss Caterpillar (Megalopyge opercularis)

Don’t let its cuddly appearance fool you – the puss caterpillar is one of the most venomous creatures in the United States. 

This little critter has long, soft hair, and sharp spies beneath those innocent-looking locks. They release toxins when they come into contact with skin. The toxin causes immediate pain and burning, as well as a rash and swelling. 

Victims may experience headaches, low blood pressure, nausea, and fever, and may become seriously ill, necessitating medical attention. 

Monarch Butterfly Caterpillar (Danaus plexippus)

The monarch butterfly is one of North America’s most well-known and beloved insects. But few people know that this beautiful creature starts life as a crawling caterpillar with a voracious appetite for milkweed. 

The monarch caterpillar (Danaus plexippus) can grow to be over 2 inches long and is bright white and yellow with black stripes arranged in partial circles around its body. 

Although it may look harmless, the monarch caterpillar has a potent venom derived from the milkweed it consumes. This venom is strong enough to sicken or even kill predators who attempt to eat it, making the monarch caterpillar one of the most feared insects in the animal kingdom. 

Saddleback Caterpillar (Acharia stimulea)

The saddleback caterpillar is a beautiful but dangerous creature. Native to the eastern United States, it is distinguished by a brown saddle-shaped spot on its back. This caterpillar is also known as a slug caterpillar due to the short length and shape of its abdominal legs. 

But these caterpillars’ tiny pompoms serve a purpose other than decoration. The pompoms, like much of the rest of this creature’s body, are covered in urticating hairs that secrete irritating venom. 

The stings are excruciatingly painful, and they can cause swelling, nausea, and a rash that lasts for days. 

So while the saddleback caterpillar may be lovely to look at, it’s best to admire it from a safe distance.

Io Moth Caterpillar (Automeris io)

The io moth caterpillars (Automeris io) are mostly light green in color, and have narrow red and white stripes that run the length of their bodies. This makes them easy to identify. 

These striking creatures are part of a wide range of habitats, from Maine to southern Canada to southeastern Manitoba, North and South Dakota, Nebraska, and Colorado; south to Florida, the Gulf states, Texas, and New Mexico; and south to Costa Rica. 

In addition to their bright coloring, io moth caterpillars also have a layer of small spines covering their backs, almost like tiny trees growing out of them. It’s best not to touch these spines. They can cause a stinging or burning sensation as they break off and become embedded in the victim’s skin. 

Despite their seemingly fierce appearance, io moth caterpillars are actually quite gentle creatures that pose no threat to humans. 

Conclusion

Even with all of this information, it is still important to be aware that not all caterpillars are harmless. 

It’s best to be safe and avoid touching any caterpillars you see, especially if you’re unsure of what type they are. With a little knowledge about the most poisonous caterpillars, though, you can help protect yourself and your loved ones.

Also, check out our guides and most effective methods on how to get rid of caterpillars if you are dealing with them in your garden, of hire professionals to help you.

Have you ever seen a poisonous caterpillar? Share your experiences in the comment section!