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Asp Caterpillar

Summary: With a mop of luxuriant hair, the Asp caterpillar may look like nothing more than a harmless, cute, furry bug, but don't be fooled this caterpillar packs a wallop.

With a series of venomous spines the Asp caterpillar sting can deliver a zap capable of causing instantaneous and severe pain along with nausea, vomiting, headaches and muscle cramps, itching, fever, and swollen glands. These symptoms, particularly the intense pain, are felt by the victim for between a few hours and several days, whilst a more mild discomfort may continue for up to a week after that. Best then, that you know what this caterpillar with the bite looks like, don't you think?


The Asp caterpillar, also known as the Puss caterpillar, is a very hairy caterpillar with fur that ranges in colour from white or pale blonde through to chesnut brown and a deep, slate gray. The body of the caterpillar narrows at its base and extends into a long, over-sized tail. Some Asp caterpillars have a dull orange streak running along the body. Typically, this caterpillar is a little over 1 inch in length although it may look much bigger because of its wild growth of hair.

The Asp caterpillar is the larvae of the Flannel Moth which has an equally odd appearance with hairy legs, black feet and long woolly hair that ranges from lemon to burnt orange in color. All in all an odd looking fellow that shouldn't be hard to miss.

The Asp, or Puss caterpillar goes by the offical moniker of Megalopyge opercularis. The Asp, United State's most poisonous caterpillar, is found mostly in Southeastern and South-central United States, Mexico and some of South America. The larvae appear in August through to September. The Asp enjoys feeding on oak, elm, sycamore and citrus trees and is also partial to a snack of roses and ivy. However, this is a yard insect that is usually found only a few at a time so any damage that it does to your plants and trees should be minimal.

Nevertheless, if the thought of its vicious sting is all the motivation that you need to get rid of this fleecy, fluffy fellow then proceed with caution. The best method to deal with just a few Asp caterpillars is by simply pulling on a pair of rubber gloves and picking them off one-by-one. Then place the captured caterpillars in a pail of soapy water to seal their fate. Once finished carefully clean the gloves and ensure that both water and caterpillar are flushed down the drain.


An alternative to this plucking technique is to use rosemary oil, a natural pesticide: place the oil in a squirty bottle and spray straight onto the caterpillars. It's not advisable to use traditional pesticides: although it will provide an immediate solution, re-infestation the following season is likely, as the pesticide will also kill the caterpillar's natural predators.

he best way to remove the Asp caterpillar's sting is by placing clean adhesive tape over the wound and peeling off. Repeat several times. An application of an ice pack may reduce the pain but a number of sting victims claim that a gauze compress of raw, chopped potato and grated ginger is more beneficial. The young, the elderly and anyone who suffers a severe reaction to any sting should seek immediate medical attention.

Ask Rick A Question


Kim Zimmermann
13 Oct 2010, 15:39

If we want to keep an asp as a class pet, how can we feed and water it? We make sure the children do not touch it.

Thank you,
Room 29
08 Nov 2010, 21:24
we have found a caterpillar just like that but it has no furry legs only furry with a orange line on the back what is it?
Ask the Exterminator
09 Nov 2010, 15:10
I cannot ID without a photo. Send it via the "Ask a Question" link at the top of the page.
11 Nov 2010, 10:12
i just got enventomated by an asp this morning by just picking up a piece of trash to put in the bin, it burns, and stings, having trouble breathing, must be a reaction, taking benedryl and trying the tape method to rid myself of toxic hairs, not careful when dealing with foilage in fall, it can hurt real bad.
16 Jan 2011, 00:23
that is a dumb thing to do keeping it as a class pet wth?? the old fashioned way get one put it in alcohol and pin the dang thing to a board for id purposes kids should be taught how to id it but not to keep as a dang pet stupid!! maybe you should just go out and pick one up then you'd know..
28 Apr 2011, 13:33
I agree...bad idea having one anywhere near anyone's kids. I was stung on my ankle while mowing last July, and was in severe pain immediately. I applied adhesive tape several times, then put ice on the sight to make the pain bearable. Later read to do the compress of chopped potatoes and this time the pain was shooting up my leg from my ankle and into my groin and lower back. Once I put the compress on the sight, within a couple of hours the pain subsided slowly from the lower back and groin, back down the leg and by morning I was pain free. Pretty sure if I had applied the compress sooner I would have avoided a lot of the discomfort, as it really seemed to draw out the toxins. I'm thankful my kids didn't get stung...get that thing out of your classroom!
28 Jun 2011, 20:19
is a IO moth rare in west virginia?
28 Jun 2011, 20:23
i aloso think that is a pretty bad idea having it as a class pet because you will nevr know if that caterpillar will be able to inject poison into those kids systems!
Ask the Exterminator
30 Jun 2011, 11:45
Io moths are common throughout eastern North America, north to southern Canada. They range west to southern Arizona and south to Central America, at least as far as Costa Rica.
01 Sep 2011, 18:55
I live in MS and I went to snap a limb off of our bush that one was on to go show hubby.. and i got stung by another one. I had to go to the ER to get shots. Was stung on the end of my finger and it swelled and turned completely red up to my shoulder. It felt like fire and it has been 6 days and still has a bad mark and itches like crazy. Our bushes in our front yard are covered in them.(each about an inch apart from eachother) They are even on our house and carport. My husband has lived in MS his whole life and has never seen them before now. Nothing is killing them and my kids have bad skin allergies as it is. :( I'm terrified to let them play outside. Also they look like this except some even have an orange looking mohawk down the back.
21 Apr 2013, 22:25
i live in Houston Texas, and have noticed the asp are everywhere. i have a question though. Are the asp dangerous for animals? we just found one in our house, and our kitten got a hold of it. She did not eat it but by the time we picked it up, it had no hair and was dead. please let me know.
12 Jun 2013, 20:43
I was stung as a kid on my inner thigh. It took about 12 hours for the venom to get out of my body. From what I remember, I was very sick. It left a scar on my leg for several years with the imprint of the insect. Stay away from those things. I also live in Houston.
05 Aug 2013, 20:27
I live in Houston and remember quite distinctly walking from my mother's front door to my car with an umbrella in case one of the zillion asps in her trees would fall on me....horrible. Last year we had them all over in our trees and a flying insect smog spray (don't remember the brand) eventually killed them all and now they are back again.
Jenny Caroline
05 Nov 2013, 18:31
I live in Houston and accidentally leaned on one with one hand while opening the mailbox with the other. I have never felt such pain in all my life- I'd rather break a bone. I have another horrible infestation, and nothing is killing them.
PS- I'm a 2nd grade teacher & it is beyond idiotic to have these in a classroom. They can temporarily paralyze a child. I can't believe ANY teacher would consider that?!?!
06 Sep 2014, 12:10
What school she teach at hell make sure my kids don't go there lol sum self,hello think about what u are saying
07 Sep 2014, 23:17
They sure are cute and so fuzzy. Its a shame that they sting because im sure lots of small kids see them and cant help trying to pick them up. If I hadn't read this and come across one id probably have a hard time not trying to pick it up myself. When they turn into moths do they still sting?

I gotta agree its not very smart having one as a class pet. Better safe than sorry with things like this. Besides a class pet u can never touch is like so uncool and wouldn't be any fun for the kids anyways. They'd lose interest quickly.
08 Sep 2014, 17:54
Grew up in Ft Worth/Dallas area. Got hit by those little blitters twice. Once on the hand and once on the ankle. I have been stung and bitten by a lot of things, plant, animal and human (I am a retired cop)and none of those hurt as bad as the asps. I still have a scar on my right hand from an encounter. We had elm trees in the yard and it would get covered with them. They would sometimes fall out of the trees as you walked under them. I don't know if that was accidental or intentional but the pain didn't differentiate between the two. I think the elm disease that killed a lot of the elms in Dallas actually got rid of a lot of them but I do remember seeing them on rose bushes too. At any rate, keep those darned things away from children for sure. My arm was swollen for days, I had a red mark from wrist to shoulder and the lymph glands stayed painful and swollen for weeks. You can handle them, the only sting is those spines down their back but when someone picks one up, it rolls into a ball with the stinging spines sticking out all around. Kinda like a doughnut from hell.
12 Sep 2014, 15:42
lol, Funny the cop would make the doughnut comparison.
22 Oct 2014, 12:18
This past weekend while on a camping trip at Lake Texana in Edna, TX, I had the misfortune of being stung in the arm twice. I did not realize the asp was on the arm rest of the chair,when I sat down I moved my arm a couple times to get situated and it stung me twice. It started stinging then burning and eventually the pain went up into my armpit, my arm throbbed, this was some of the worse pain and I have given birth naturally without any epidural. I went up to the check in office and the security guy told me to put chewed tobacco on it.He didn't mention to remove the hairs and I was not aware that you needed to use tape and remove the hairs first, so I had put a compress of chewing tobacco on it and wrapped it with gauze, with the hairs still there. That was on for a few hours before I removed it. I was in pain for a couple of days.
02 Nov 2014, 21:57
Just got hit by one! Man does it hurt bad. Thing is that it only got me with a couple of hairs!!! I could only imagine it hitting me more then what it did. Rose oil will kill them and don't use pesticides because it kill the predators that eats it. Rosa oil is a natural pesticide that kills only a few insects and this is one of them. If you kill the with poison, it only kills them now but the egg will live for next season and no predators to eat them. It will take a two to tree year cycle to get rid of them. As far as the teacher is concerned. No need to belittle her or him. The teacher that's doing this. I know you are trying to teach this kids about the dangers as well as the Beauty of these little guys but it's not a good idea. someone could get hurt and then it lies on you. Something you were just trying to make the kids enjoy and as be aware of. So good luck to all and remember! "Karma is always watching and waiting for you!" That can be worse then the little boogers were talking about.........
14 Nov 2014, 23:20
I live in the valley in Texas. When I went to a park a light brown asp got onto my leg and I squished it with my elbow on accident and I felt like little spines on my arm. It about 15 for the pain to kick in and when it did, it was just hell and I wasn't with my family so it was really hard and we couldn't go to a doctor. The pain lasted for about 12 hours and I couldn't breathe and I kept having panic attacks and it was jus horrible.
Beverly South Texas
25 Nov 2014, 16:37
I live in south Texas also, my poor little dog that weighs 5 lbs. was stung by a asp Sunday. the poor little thing cryed. I gave him benedryl and put a ice pack on him. It took about 8hrs before he could walk on his leg. He also couldn't breathe,he was so stressed.
16 Apr 2015, 19:46
Is there insecticides you can put on the trees to reduce the amount of these annoying insects so you can enjoy the outdoors without the worry of being stung?
Mike Spark
27 Jul 2015, 16:40
Have been seeing a bunch of asps on the siding of our house, in our shrubs, trees, everywhere. Like an infestation. Also, just noticed a web all over our trees yesterday, like a web worm, but much finer web, like silk. I've never seen an asp do this but don't know of anything else that does.
Ask the Exterminator
28 Jul 2015, 10:32
The webbing sounds like Eastern Tent caterpillars.
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