Currently viewing the category: "Asps and Flannel Moth Caterpillars"

Stinging Caterpillar
Location: Guanaja, Honduras
April 26, 2011 11:14 pm
What is this caterpillar? It has a severe sting.
Signature: ??

Stinging Flannel Moth Caterpillar

Dear ??,
We have posted images of the stinging Flannel Moth Caterpillar,
Megalopyge lanata, several times in the past.  We are going to take this opportunity to create a new subcategory for Flannel Moth Caterpillars.  We love that your photo illustrates two different instars of this dangerous caterpillar.

More Catapillars
Location: Houston, Texas
March 21, 2011 9:59 pm
These pictures were taken October 23 2010. The catapillar I’m most curious about is the tan one in all three pictures. Me and my sister thought it was super cute. The other catapillar in the third image is less cute and really familiar looking, I think because I’ve seen that type of catapillar a lot growing up. What kind of catapillar is that little tan one? If it’s easy to identify, what is that yellow striped one?
Signature: Thanks a lot, Kelly Bufkin


Hi Kelly,
Your tan caterpillar is a Puss Caterpillar or Asp, the larva of the Southern Flannel Moth,
Megalopyge opercularis.  Handle the Asp with care as it is a stinging caterpillar.  The yellow striped caterpillar appears to be one of the Prominent Caterpillars, possibly Datana contracta based on images posted to BugGuide.

Prominent Caterpillar meets Asp

wild larva
Location: Davie, FL
December 12, 2010 2:21 pm
Bugman, I consider myself somewhat of a pro at south florida lepidoptera as i was a professional butterfly breeder for a few years, but I found a larva today that I’ve never seen. While I was excited at seeing something new in my own backyard, not knowing what it is frustrates me to no end! Please help. Found it on the ground under some sea grape and oak trees.
Signature: Brett


Dear Brent,
You have encountered the infamous Asp, the caterpillar of the Southern Flannel Moth,
Megalopyge opercularis.  It gets its common name as it is quite capable of delivering a painful sting.


Thanks very much for your confirmation.  Shortly after emailing you I figured it out, but thanks very much for your help anyway!  You provide a great service.

Unknown caterpillar from Peru
May 22, 2010
I found this caterpillar on a walk through the Peruvian Amazon. It was about 2.5-3 inches long. I tapped the branch it was on to try and collect it, but some of the hairs started coming off so I decided to just take a picture.
Quincemil, Peru 640-800m in SE Peru

Asp from Peru

Dear Clayton,
In North America, there is a group of caterpillars in the Flannel Moth family Megalopygidae (which is represented on BugGuide) that are commonly called Asps.  Asps, which are also known as Puss Caterpillars, are stinging caterpillars.  We suspect your specimen is closely related to the Southern Flannel Moth, Megalopyge opercularis which is profiled on BugGuide.

Fuzzy, slow, brown/white
December 6, 2009
We found this little bug on the wall of our entry way. At first we thought it was a mud-dauber hole but then it was in a different spot the next day. It moves extremely slow.
North Texas



Hi Joe,
This is the stinging caterpillar of the Southern Flannel Moth, Megalopyge opercularis, and it is called an Asp.

Venomous Mexican Stinging Caterpillar
Sun, Feb 15, 2009 at 9:29 AM
I am wondering if anyone knows what sort of caterpillar this might be? It was about 1″ long, a creamy light green color, and was covered with very long dark brown hairs. It was originally much fatter than shown in the photo – by the time the photo was taken, it had dehydrated a bit due to being carrying around in a plastic bag trying to get it identified. Unfortunately I just had a very nasty encounter with one of these, in in the Yucatan peninsula of Mexico (Isla Mujeres – just off the coast by Cancun). It dropped out of a tree and stung me on the leg. It immediately felt like the burn of a bee sting but rapidly progressed beyond this. Caused a large welt and redness and swelling of sting area about 6″ around. But the worst part was the systemic effects of the sting which were horrible (incredible back muscle spasms, tremendous abdominal pain, and intense nausea) such that I ended up in the emergency room. Have looked on the internet to try to find out what it was, but have also been unsuccessful in determining this. Even the locals there couldn’t tell us although most knew that it was very painful and to be avoided at all costs. Any entomologists out there looking for a challenge??? Would sure love to know what this nasty little bug was…
Isla Mujeres, Quintana Roo, Mexico (Yucatan Peninsula)

Unknown Stinging Caterpillar

Flannel Moth Caterpillar

Hi Yvonne,
We haven’t the time to research this at the moment, but perhaps a reader can provide the answer. We don’t believe this is a Stinging Slug Caterpillar in the family Limacodidae because they don’t generally have hair. We really hope to properly identify this specimen for you and add your public service message to our archives.

Update: Eric Eaton contacted Doug Yanega who provided the following ID:
Tuesday, February 17, 2009
That’s the larva of a Megalopygid, probably a Megalopyge species near
M. lanata
The long hairs are not the stinging hairs; the stinging hairs are
short, arranged along the side of the body not far above the prolegs.
Doug Yanega
Dept. of Entomology
Entomology Research Museum
Univ. of California, Riverside, CA

I was curious, so I asked around.
could use an identification and maybe some warnings, given that Spring Break is about to happen. The critter looks pretty tame, actually, not spiny like you tend to associate with venomous ‘pillars.
Please credit Doug with this. Thanks. Eric.

Ed. Note: Moths in the family Megalopygidae are known as Flannel Moths and the Caterpillars are sometimes called Asps because of the sting, or Puss Caterpillars.

Tuesday, February 17, 2009
Hi Daniel:
This looks like the caterpillar of the Flannel Moth Megalopyge lanata (family Megalopygidae). It has appeared on WTB before (Unknown Panamanian Caterpillar on Cashew Tree – April 5th, 2008) and a lot of good information was given in response to that post. It is widespread throughout Central and South America and is definitely a creature to be wary of. Regards.

Thanks for the info! Indeed, the photo noted below is a dead ringer for the
guy that stung me.
I have put a link to your website on an information site for the island,
just so that others can be aware and give a wide berth to this nasty little
Thanks for all your help
Yvonne Hillsden

Friday, , February 20, 2009, 3:21 PM
Saw the post about the stinging caterpillar earlier in the week. the systemic symptoms sounded familiar to something I had come across recently. You may or may not want to share the attached pdf (cmaj-death-from-caterpillar ) with Ms. Hillsden.
Jeffrey B. Tucker, B.C. E.
Entomology Associates, Inc.
Houston, Texas

Update: Sun, Feb 22, 2009 at 10:07 AM
Hi Daniel,
Thanks for the heads up.  I had read the CMAJ article already (just after I had been stung actually) and frankly it had scared the crap out of me!  That was one of the reasons why I was so anxious to have my particular culprit identified.  I was very relieved when the entomologist from CA identified my guy as a flannel/puss moth sp.  Would definitely not have been happy to hear that it was a type of lonomia!
Who’d ever think these cute little furry guys could pack such a nasty punch!