Friday Caterpillar Blogging: Puss Caterpillars

Puss Caterpillar

Puss Caterpillar
Photo: Donald W Hall

Puss caterpillars have “furry hairs” that resemble the fur of a pussy cat. Thus the name, puss caterpillar. However, don’t try to pet one like a pussy cat; the caterpillars have venomous spines and are among the most toxic caterpillars in North America. Puss caterpillars are the immatures of flannel moths of the family, Megalopygidae. Eleven species are described from North America, mostly found in the Southeast of the United States. The southern flannel moth, Megalopyge opercularis, is the best known. Occasionally, large (usually localized) populations appear and more people, unfamiliar with the creatures are stung. In Texas, outbreaks have led to school closures because of the number of school children stung. Donald W Hall has a great website about the Southern Flannel Moth with excellent pictures and biological information.

This year (2013), southern flannel moth populations in Northern Virginia are larger than is typical resulting in more reports of stings. What to do if you are stung? Jerry Cates of Bugs In The News discusses options and evidence. When pressure is placed on the caterpillars, tiny, venom-containing hollow spines penetrate the skin. The venom leaks from the hollow center of the spine under the skin. In numerous cases, spines have been successfully removed by gently pressing clear adhesive tape (Scotch brand magic mending tape, duct tape and medical bandage tape are all reported to work) onto the sting site. The spines stick to the tape and are pulled out of the skin when the tape is removed. This process is repeated several times to remove the majority of the spines and the venom remaining within them. The tape does nothing for venom that is already under the skin which may take time for the body to degrade.

A sting victim who went to an emergency room reported her experience:

It was like nothing I ever experienced … it was excruciating, it did not let up at all, so the whole time I was in the emergency room I felt like I was being stung. …Every minute that went by, I felt worse and worse… It felt a lot better almost immediately when I used the tape….I hope it goes away,” she said. “It’s still painful to touch.

The moths and caterpillars are both beautiful creatures, aesthetically pleasing from a safe distance. The caterpillars are definitely “look but don’t touch”. Jonathan Wojcik has a video on YouTube:

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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18 Responses to Friday Caterpillar Blogging: Puss Caterpillars

  1. Anonymous says:

    Although the puss caterpillar has a cute look, it really has dangerous toxin inside. As it mentioned in the passage, in Texas, the outbreaks have led to school closures because of the number of school children stung. I think the “look but not touch” mention is really important for everyone.

  2. Anonymous says:

    I would have never guess that something so furry looking could be poisonous and in fact I didnt even really know that there were poisonous caterpillars to begin with! Im also curious as to what happens when it turns into a butterfly?

  3. Anonymous says:

    It’s amazing the different ways that insects can defend themselves. I never would’ve imagined that the “fur” on the puss caterpillar would be so poisonous. After looking up images of the Flannel Moth, it’s still weird to see an insect that looks like you could pet it! This is definitely an insect that could be very dangerous around children that don’t realize how harmful it could be.

  4. Anonymous says:

    The puss caterpillar is very interesting. I find it humorous that it is compared to a furry cat but I definitely see the resemblance! I also was very surprised that it is poisonous because most furry animals are not furry!

  5. Anonymous says:


  6. Anonymous says:

    When I first saw a picture of the puss caterpillar I did not even realize it was a caterpillar. It appears as just a little fluff ball. However, even though the cute fuzzy insect seems harmless, I would never want to be close to one after reading about it. It is just crazy that it can be so toxic.

  7. Anonymous says:

    The puss caterpillar sounds and looks very frightening. I could imagine small children being amused by them and touching them. It is scary to think that something so small and harmless-looking can be extremely dangerous with venom. However, I interested to find out what happens when they turn into butterflies.

  8. Anonymous says:

    The puss caterpillar looks so cute, never thought that caterpillar can have fur. It is amazing how insects have different kinds of features to defend themselves. Also, with those special looks, children might attracted to it, which parents should consider more about.

  9. Anonymous says:

    It’s interesting that they pupate in their own skin, as opposed to a cocoon. An excellent example of “looks can be deceiving.” It’s a great defense mechanism, too. They look so harmless. It’s crazy that something so small can cause such a great pain.

  10. Paige Keough says:

    I didn’t even know that different types of caterpillars exists. It’s interesting that they compared it to a furry cat because furry cats, mostly, like to be touched and pet. This caterpillar is the opposite of that and it stings you if you touch it and it contains toxins inside of it. I can’t believe how that victim went to the hospital and said how the pain got worse and worse and how excruciating the sting was from such a small and tiny creature.

  11. Anonymous says:

    It is incredible that these caterpillars are in the United States and are so dangerous, yet unheard of. I want to know on what predator they use this defense mechanism on. It is also very interesting that the poison is stored in the soft fur.

  12. Anonymous says:

    When looking at these caterpillars at first glance, one would not realize that they are so dangerous due to how cute they appear! Considering that the fur is such an interesting and adorable aspect of the caterpillar, it is shocking that the toxic poison is located inside the softness. This article gives an insight to the several different types of caterpillars.

  13. Seth W. says:

    This caterpillar is definitely not to be judged by its appearance. The world of insects is so unique in the variety of ways different insects develop defensive mechanisms. I find it odd that this caterpillar lacks any kind of overt warning signs like bright coloration to warn of its toxicity. It just appears to be a friendly fuzzy caterpillar that, had I not been warned, I would have happily tried to touch. Just goes to show that you should never judge a book by its cover!

  14. Anonymous says:

    This caterpillar is definitely an insect that could’ve been easily misjudged. I think the fact that the caterpillar lacks the warning signs that most toxic insect/animals have is really peculiar. But at the same time, I think it gives this insect a serious advantage in the grand scheme of things. Someone or something would easily just go pick it up or try to eat it without even thinking “you are dangerous and toxic.” It’s almost disappointing that it’s so toxic because you just want to touch it based on the cute appearance, but it’s clearly given these caterpillars the survival advantage they need.

  15. Anonymous says:

    I think the article on the puss caterpillar is the most interesting topic. It’s interesting because it is new information for a lot of people. I find it very shocking that a fury caterpillar can be harmful to touch.

  16. Taylor says:

    It is so interesting that such a cute insect could be so dangerous! I’m glad that I’ve never seen one because I probably would’ve touched it. Good thing I now know how to get rid of the spine, though!

  17. This really isn’t that interesting or surprising. I’ve seen quite a few caterpillars in my day. Once, I touched a furry caterpillar and had itchy symptoms hours after. I did, however, find the fact that these certain caterpillars turn into moths. Poisonous butterflies, yeah right!

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