Stinging Caterpillars Identification and Guide
Stinging Caterpillar Identification
Most caterpillars are completely harmless and rely on camouflage to avoid being eaten by a predator. A few of them, however, have evolved stinging spines and hairs. If you handle one of these stinging larvae, there's a chance you could wind up with a painful sting.
This guide will help you tell the stinging caterpillars from the harmless ones. Many caterpillars that have fur and spines look like they can sting, but can't. Other caterpillars, like the dangerous species known in southern states as "the asp," hide sharp stinging spines under harmless-looking fur.
It's important to be able to tell whether the caterpillar you find is able to sting you. Your reaction to these stinging substances may be as small as a minor rash to as serious as a trip to the emergency room. While none of these caterpillars can kill you, some can give you a serious sting that can last for a week or more. If you're stung by a caterpillar and you feel short of breath or begin to experience swelling, call 911 immediately -- some people are allergic enough to require medical treatment.
It's always good to know as much about the natural world as you can, and some things, like stinging animals and insects, are a matter of personal safety! So while the vast majority of caterpillars are completely harmless (except to leaves), there are some that are definitely worth getting to know.
This is the most common stinging caterpillar and also one of the most toxic. If you have ever been stung by an "asp," as they're known, you will likely remember it for a long time -- which, from the caterpillar's point of view, is the whole point.
These insects are technically in the family Megalopygidae, but the common name for these odd creatures, "asp," is more descriptive -- it refers to the snake-bite severity of their sting. The sting of this species has been described as "often very severe, radiating up a limb and causing burning, swelling... with headache, abdominal pain, skin rashes and blisters, and even chest pain or difficulty breathing." (Eagleman 2008) Allergic reactions to asp "bites" can be scary but are not typically life-threatening. Still, if you or someone you know is stung by one of these caterpillars, you should call your doctor right away.
Another Asp "Hairstyle"
Sometimes called the Elvis caterpillar, stinging asp caterpillars come in a variety of "hairstyles." The brown version is more common in the southeast. Sometimes these caterpillars will drop out of trees on their way to burrowing into the ground to pupate. Occasionally they'll land on a person, on the back of a neck or an arm, and that's when most stings occur.
The Saddleback Caterpillar
These caterpillars are in the family Limacodidae, which has a number of similar, slug-like caterpillars, many of which sting. You may well encounter one of these caterpillars when you're gardening. Like a lot of stinging caterpillars, they are slug-like and slow. Waiting them to move out of your way is time-consuming, so use a stick or leaf to roll them off, if need be, onto the ground. They'll find their way back to the food source eventually.
A Group of Saddleback Caterpillars
My Experience With Insects
Although I'm a history teacher by profession, my career as a citizen scientist spans four decades. My paternal grandfather, Arthur Cushman, was an artist who worked for the USDA and The Smithsonian Institution. On occasion he would send me cast-off specimens from the museum collection, and I was a devoted entomologist by the time I was seven years old. As an adult, I have taken my obsession to the next level: I camp alone in jungles and deserts, seeking insects tp photograph, collect, and record; I donate specimens to museums and studies; and I am in the process of building an online database of all the insects on a small island in Panama. I also draw insects, and I currently have an exhibit of original pen-and-ink artwork on display at the local nature center.
The Stinging Rose Caterpillar
This striking caterpillar can sometimes be common on rose bushes, where gardeners occasionally brush up against them and receive a sting. There are several species in the Parasa genus, all quite similar. The moth of this species is really attractive, a rich chestnut brown with deep green markings. It's quite well camouflaged, though, so you'll probably never see one in real life.
The Spiny Oak Slug
One of the most gorgeous caterpillars out there, in my opinion, but still capable of giving you a sting. It's not super-poisonous, but you'll definitely feel the burn. All of those little spines on the insect's back contain an irritating venom, and if you brush against it you'll get stung. The bright colors, as with many stinging caterpillars, are probably a way of warning predators, and people, from even getting close enough to find out how poisonous this animal really is.
Another seldom-encountered but venomous caterpillar is the larva of Norape ovine, a Limacodid that occurs in much of the eastern United States. These caterpillars are small but easy to spot, with their bright white markings on a dark background. The venom is conveyed by special hairs that are hard to see, but when they brush your skin, you'll feel a sting. I have found the adult moths to be not uncommon, but I've never seen the caterpillar in nature.
The Monkey Slug Caterpillar
Truly a weird critter, even in the company of other weird critters. The monkey slug bears stinging hairs on its "arms," which are not really arms but just fleshy appendages sticking out from the animal's sides. These caterpillars are not terribly common, but if you come across one handle with care, because the hairs can give you a wasp-like sting. They become an inconspicuous moth called the "hag moth."
A Very Cool Video of Stinging Monkey Slug Caterpillars
The Giant Leopard Moth Caterpillar
This large caterpillar can sometimes be found curled up under stones or logs, where it overwinters. The spines of this species do not contain and toxins, but they are extraordinarily sharp and stiff, and could cause some slight damage if handled carelessly.
Another caterpillar in the Limacodidae family, Isa textual is known as the "crown caterpillar" due to its nearly spherical shape and spiky edges. The moth doesn't have a common name and is relatively uncommon, but it's a pretty faun color with furry legs. You will on occasion find these larvae on maple trees in early fall, and if you do you should treat it with respect.
The Io Giant Silk Moth Caterpillar
These caterpillars eat the leaves of roses and related plants, and often stay together in groups of a dozen or more. I have raised these caterpillars from egg to adult, and of course had to see if they really sting. I can safely report that they do. My arm was red and burning for about an hour. It wasn't intense, but it definitely made me give these big, showy caterpillar a little more respect.
Another view of the Io moth caterpillar:
Caterpillars are the immature form of butterflies and moths. They hatch from eggs laid by a fertilized female, and quickly begin eating and growing. In the cycle of forms that every butterfly and moth undergo (known as "complete metamorphosis"), the caterpillar is the phase that accumulates and stores fat and energy. The adult moth or butterfly eats relatively little; their task is to reproduce and lay fertilized eggs.
The caterpillar will shed its skin several times as it grows. Finally it becomes a pupa, during which time it does not move but changes radically inside the pupal shell. Moth caterpillars spin a cocoon around the pupa. The pupa of a butterfly usually hangs from the food plant and is called a "chrysalis."
Complete metamorphosis occurs in many other kinds of insects, including beetles, bees, cicadas, and dragonflies.
The Buck Moth Caterpillar
These insects are not particularly common, but once in a while they'll undergo a population explosion and you'll find a number of them munching away on your backyard oak tree. They travel in big groups, and when you find one you usually find many more. The spines are extraordinarily sharp and a bad sting can linger for more than a week. These guys are related to the io moth.
The White-Marked Tussock Moth
In my experience these caterpillars do not sting, and I have handled tons of them, because they're among the most common caterpillars in North America. But they do have irritating spines, and if you're sensitive to insect bites and skin irritations in general, you should probably steer clear of these amazing-looking caterpillars. They tend to have population explosions on a wide variety of trees, including ornamental varieties planted along parkways and in public plazas.
Variable Oakleaf Caterpillar
This caterpillar comes in a bewildering array of colors and patterns -- some individuals don't even look like they belong to the same species. There are reports that this insect possesses a gland near the head that can spray formic acid if the caterpillar is disturbed. Formic acid is also used by ants and some other insects for protection, and it can cause a burning sensation. While not dangerous, this unique form of protection makes this caterpillar one to watch out for.
While it is, as the name suggests, quite variable, this description of Lochmaeus manteo from Alabama University is useful:
"The head is greenish with a vertical black stripe on each side, bordered on the outside by a cream to white stripe. The base color of the body is green. There is a narrow yellowish, cream, or white line down the midline of the back, and wider cream or white lines along the edges of the back. Coloration of this back area is highly variable (thus the common name), and ranges from green to reddish brown with gradations between."
This South American Caterpillar Can Actually Kill You: Lonomia obliqua
This South American species is related to the stinging io and buck moth caterpillars described on this lens. Unfortunately for its victims, the sting possessed by this caterpillar can lead to uncontrolled internal bleeding and death. In rural areas of South and Central America, Lonomia obliqua caterpillars often rest on tree trunks, where they are very well camouflaged. Farmers and other people working outside sometimes brush up against them, and in severe cases the sting can be fatal.
Please note that there are no caterpillars in North America, Europe, or other temperate parts of the world that are similarly toxic!
The following sources were used in the production of this guide: