Few other larvae are as captivating as the caterpillar. The juvenile form of butterflies and moths inhabit the world of charming creepy-crawlies, like ladybugs and fireflies—the kind of insects that are more Lewis Carroll than Franz Kafka. Caterpillars are high in protein and rather defenseless—making them an easy dinner staple for other animals—and many have evolved various means of protection. Their markings and body parts can make them seem larger in size and some of them are poisonous, both to consume and to the touch. But before you go out and start squishing caterpillars, remember that they are not vicious, and stinging only occurs when they are touched and feel threatened.

1 of 8 Puss Caterpillar (Megalopyge opercularis) arnwald / Getty Images Bearing a resemblance to Cousin Itt of the Addams Family, this guy goes by the name of puss caterpillar, or asp. Puss, because this caterpillar is as fuzzy as a kitty; and asp, as in snake, because this is one of the most toxic caterpillars in North America. The venom comes from poisonous spines neatly concealed by the irresistibly fuzzy surface. When touched, the spines break off and lodge in the skin, releasing the venom. Mother Nature at her sneakiest. According to the toxin library of the American Association of Clinical Chemistry (AACC), this is no simple sting: Intense throbbing pain develops within five minutes of contact, with pain extending up the affected arm. Other symptoms may include headaches, nausea, vomiting, intense abdominal distress, lymphadenopathy, lymphadenitis, and sometimes shock or respiratory stress. Moral of the story: Step away from the world’s cutest caterpillar.

2 of 8 Saddleback Caterpillar (Acharia stimulea) JasonOndreicka / Getty Images The beautiful saddleback caterpillar is native throughout the eastern United States. Identified by the brown saddle-shaped spot on its back, the saddleback is also called a slug caterpillar because of the short length and shape of its abdominal legs. The pert pompoms these caterpillars sport are more than decorative. Like much of the rest of this creature's body, the pompoms bear urticating hairs that secrete irritating venom. The stings are very painful, and they can cause swelling, nausea, and leave a rash that can last for days.

3 of 8 White Cedar Moth Caterpillar (Leptocneria reducta) Bidgee / Wikimedia Commons / CC-BY-3.0 The white cedar moth caterpillar is found throughout Australia and is partial to the Cape Lilac (also known as White Cedar) Tree. The caterpillar is most active during warmer months, and it tends to look for shade during the heat of the day under houses and other structures. Reminiscent of an angora sweater, this caterpillar can indeed pack a punch—the bristles are capable of inducing a frightful case of urticaria, or hives.

4 of 8 Io Moth Caterpillar (Automeris io) Weber / Getty Images Like a tiny oasis of palm trees, the sweet, colorful io moth caterpillar has a broad range, 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 from Mexico south to Costa Rica. And yes, those frond-like spines have a painful venom that is released with the slightest touch. Some people experience severe reactions and require medical attention, while others only have an itching or burning sensation.

5 of 8 Hag Moth Caterpillar (Phobetron pithecium) Greg Dwyer / Wikimedia Commons / CC-BY-SA-2.5 Question: Cute fuzzy octopus monster that could be a plush toy? Or, an arachnophobe’s worst nightmare? Whichever camp you’re in, one thing’s for sure: there’s little mystery as to why this caterpillar garnered the nickname “monkey slug.” Complete with six pairs of curly projections densely covered in hairs, the “limbs” can fall off without harming the larvae, but the hairs can cause some fierce irritation.

6 of 8 Hickory Tussock Caterpillar (Lophocampa caryae) Mod Quaint / Getty Images Dapper, with its velvety back and sweeping bristles, this creature looks more vintage feather boa than larva—but larva it is. And stinging larva, at that. Although some people have little to no reaction to this caterpillar, others have a reaction that ranges from a mild to a fairly severe rash comparable to poison ivy.

7 of 8 Pine Processionary Caterpillar (Thaumetopoea pityocampa) Scacciamosche / Getty Images Somebody needs a haircut—but then somebody would be much less dangerous and not nearly as cute. The larvae of the pine processionary moth could be the model for caterpillar shampoo if there were such a thing. But all that hair, touchable as it may look, should never be touched. Not only are the extremely irritating hairs harpoon-shaped, but the caterpillar can eject them when threatened, at which point they penetrate all areas of exposed skin, replete with urticating venom.

8 of 8 Giant Silkworm Moth Caterpillar (Lonomia oblique) Rosa Caroline Teixeira / Flickr / CC BY-NC-SA 2.0 Nature got it right with this one—it's designed it to look as scary as it is. This is not the caterpillar you want to meet in a dark alley. Known as the "assassin caterpillar," the South American larvae are responsible for over 1,000 cases of poisoning from 1997 to 2005, with many leading to death. The spear-like bristles penetrate the skin and deliver a dose of toxin that leads to headache, fever, vomiting, and malaise before a severe bleeding disorder ensues, leading to ecchymosis, hematuria, pulmonary and intracranial hemorrhages, and acute renal failure.