THE MOST TOXIC CATERPILLAR IN THE UNITED STATES!
This page was born 11/23/2003.  Rickubis designed it.  (such as it is.) Last update: 8/11/2014
Images and contents on this page copyright 2002-2014 Richard M. Dashnau

Yes, it is, according to some sources. This means toxic to the touch. I have no idea how poisonous these are to eat.

7/23/2014; 08/03/2014  A few weeks ago (7/27/14), I found an "asp" caterpillar on one of the Water Oak trees on the Live Oak Trail at the park. (the attached image is of that caterpillar) At the time, I thought this was a few months early, since my recollection was that we would see these caterpillars around October. Then on 8/03/2014 I found one (just one) on an Oak Tree near the Observation Tower at 40 Acre Lake. I also saw what appear to be many cocoons made by these insects.I decided to look again for more detailed information on this insect.
     

As a reminder, the caterpillar called an "asp" in Texas is the larva of the Southern Flannel Moth (Megalopyge Opercularis). There are a number
of references to this insect online--but I found 3 very good ones this time. The links I have here were good links today-08/11/2014 and
refer to pdf files that can be downloaded for free.

1) An early study of the asp, from 1922 ( Foot NC. Pathology of the dermatitis caused by Megalopyge opercularis, a Texan caterpillar.
Journal of Experimental Medicine 1922; 35:737–753) gives a detailed description of the physiology of the poison-delivery system, and
details observed effects of evenomation to human skin. From the detailed drawings and photos in this study, one can see the
general shape of the venom-bearing hairs. They are hollow, with a bulbous base which contains the venom sac.  Some of these hairs have had the tip broken off, but apparently they can still penetrate human skin. The study can be found at this link):http://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC2128124&blobtype=pdf

2)A later study (Envenomation by the asp caterpillar (Megalopyge opercularis), by David Eagleman) gives more details on the evenomation by the asp.  Some interesting things from this study include photos showing the distinctive "grid" pattern, or rash, produced by the contact of the caterpillar spines with human skin.There is also an effort to define the geographical distribution of these caterpillars. This is generally southern states from Texas east up to Maryland, as well as Arizona, Arkansas, North and South Carolina. Envenomations had been reported for almost all 12 months, with February being the low spot. It also showed 2 peaks of reported incidents-one in July, and one in October. This study also describes some treatments.The study can be found here:
http://www.eaglemanlab.net/papers/Eagleman%20Asp%20Caterpillar%20Clinical%20Toxicology.pdf

3)Finally, I found this information: Puss Caterpillar (Larva), Southern Flannel Moth (Adult),Megalopyge opercularis (J. E. Smith 1797) (Insecta:
Lepidoptera: Zygaenoidea: Megalopygidae, by Donald W. Hall)--published in 2012. This article features some very good color photographs showing the life cycle of the Southern Flannel Moth. These include macro photos of the eggs, and the various instars of the caterpillars as they grow to the final familiar "wooly slug". ALL of the stages are venomous. There are also references some of the habits of the caterpillar (for instance the larva (caterpillar) eats its molted exterior as it grows--including the poisonous spines. It also "propels its fecal pellets". The asp has some natural enemies,including some species of wasps and flies that use the caterpillars to incubate their eggs. Consumption of their molts and projection of the pellets may make the caterpillars harder for these potential parasites to track them. This study may be found here:
http://edis.ifas.ufl.edu/pdffiles/IN/IN97600.pdf

From what I've read on the links above, it appears that we've just seen the end of the first seasonal appearance of the asps; and in a couple more months, we may see them again.

09/05/2010 --I noticed some odd-looking moths on some of our buildings (I saw some on the 40Acre Lake bathrooms, and we had them on the door to the breezeway on the VC.).  I thought they looked sort-of like honeybees wearing fur coats.
They appear to be Megalopyge Opercularis; aka the Southern Flannel Moth. These are the adult form of one of our nastier critters--the asp caterpillar. So, for those who have been asked what the adult asp looks like--now I can say. This might also mean that we'll have another "bloom" of them this year. Last year, I only knew of them on a single tree by the Observation Platform in 40 Acre Lake. The pictures below show the adult moths.

----
  Southern Flannel Moth  (adult "Asp Caterpillar")         Southern Flannel Moth (Megalopyge Opercularis)                                         

10/21/2006 ASP ALERT--I was walking out of my apartment today, and I turned to pull the door closed. I glanced up over the door (I usually do this while looking for small creatures), and I found a caterpillar known here as an "Asp". This is also known as the "puss caterpillar" or "wooly slug", and is known by the latin name of Megalopyge opercularis.
As I looked around, I quickly found 6 more Megalopyges in the area around my door. Strangely enough, I didn't notice an around the apartments on either side, but I didn't really want to wander around in front of their windows. Among the asps I found, I saw those with the familiar gray or ash coloring; but I also found a few "blonde" ones, with a much lighter tan coloration. With the opportunity at hand, I shot some pictures and video clips of moving asps. Some of them can be seen below.

----
                          GREY A ONE                                                              GREY A TWO                                                              GREY A THREE                          
                                                                                                    GREY A CRAWLING  9.0MB    GREY A CLOSEUP  3.5MB


-----
                           GREY A  FOUR                                                                    BLONDE A

The second one I noticed was moving around quite a bit. In the images above it is "GREY A". Image GREY A ONE is a top view. GREY A TWO shows a quarter with it. GREY A THREE is a frame from a video clip showing it crawling on my doorframe, and GREY A FOUR is a single frame from another video clip showing it in closeup as it crawls through the camera view. The image BLONDE A above shows the lighter variant color with a quarter.
---
    BLONDE B ONE                                            BLONDE B TWO                                         BLONDE B THREE                                 YOU TALKIN' TO ME?
                                                               BLONDE B  CRAWLING  4.5MB               BLONDE B FACE-ON  5.8MB
As I watched the caterpillars, I noticed a large one coming down from my upper floor. This was another blonde one, but nearly twice the size of the others. It's not quite so apparent from the pictures above, but that's because of their ability to stretch. This one was noticeably larger than the others. The image BLONDE B ONE above shows it with a quarter. BLONDE B TWO is a frame from a video clip. BLONDE B THREE is a frame from the last video clip. For this one, I place the camera nearly under it as it moved down. It was at least 3 feet above my head, and I didn't want to be under it if it fell. I climbed onto a ladder to get the picture with a quarter.
It's been a few years since I did the story about these caterpillars, and I hadn't seen many of them since then. Perhaps all the rain we've been getting has made conditions favorable for them. I've also seen some asps as Brazos Bend State Park, but not as many in a small area as this. That may have changed since last week, though. In any case, be aware that they have "bloomed" so watch what you lean on!

October 19, 2003  Last week's look at the "puss caterpillar" awakened my curiosity.  So this week, I decided to  examine a Megalopyge opercularis a bit closer. I bought some latex gloves, and when I found another asp (it wasn't hard. I found 3 asps in about 5 minutes. See FROM THE TOP, below, which was one on the garage door.), I put it into one of my plastic vials, and brought it inside. After I set up my camera and a microscope, I put on a pair of latex gloves;  then another pair of latex gloves; then I put "finger cots"--short latex covers--on top of the gloves. When I finished, I had about 5 layers of latex on my index finger and thumb. If I had gotten stung through that, I would have been very impressed.  See? I'm not  crazy!
Then, I put the asp onto a plastic lid, and took a few short video clips.  Today's RICKUBISCAM shot is a frame from one clip, a fairly close view.  See the clip here (flv video 453 kb).  Here is another clip (flv video 455kb) of a much closer view. One frame of this second clip is shown as MUCH TOO CLOSE, below.

--------------------------------------
                                                        FFROM THE TOP                                                                   MUCH TOO CLOSE
I intended to touch the Megalopyge, and then see if I could find any evidence of needles or liquid (poison) on the glove. Although there might have been a few "hairs" stuck to the latex (the microscope was about 40x, and the macro shots are about 30X), I couldn't really see any evidence of needles. If I can, perhaps I'll try again. I wonder, though, if perhaps latex has enough different properties than skin to prevent penetration of the needles that I've read about.  After a while, I *did* start to feel discomfort and tingling sensations in my finger. However, that was from all the layers of gloves cutting off my circulation (ha ha ha--false alarm!).
If you look closely at the end of the "further away" clip, you'll see the asp looking up at my finger (its little button head appears); as if to say "Are you STILL here? You should be screaming about now. ".
After my examination and filming, I put the Megalopyge back into the vial, and released it back outside, on a tree *far* from any buildings or benches. After all, asps don't *intentionally* hurt people. Actually, the times people get stung are generally when they have crushed an asp (accidently or not). So, I let the poor youngster go. They're just trying to protect themselves and live to old age...just like we are.
Actually I kind of admire the fact that this relatively tiny creature can almost totally incapacitate an animal as large as a human just by standing there. Talk about walking softly and carrying a big stick!

October 12, 2003  It looks like it isn't much of anything; just a tuft of fur, or a large dust ball. But, they turn up where you least expect them, like on walls or rails or benches or similar spots that people like to lean on or lean over. And then, when you lean on one, it feels like you ARE GOING TO DIE!  Although you might wish you did, you won't die, though.  This is a caterpillar, a larva of the Flannel Moth (see WATCH OUT!, below). The latin name is Megalopyge opercularis. The generally accepted common name is "puss caterpillar"; but here in Texas, they are generally called "asps".  A quick search of the internet also turned up the very descriptive name "wooly slug".  According to one website, these are the most venomous caterpillars in the U.S.  They are not too large, about 3/4 inch long, and not very striking in appearance. In fact, with all that hair, they look almost "cuddly". But, hidden within the hairs are removable hollow spines that contain strong venom. Contact with these spines immediately causes intense pain, rash, blisters, and even nausea. I've read that one remedy is to use adhesive tape to pull the spines out (which can perhaps stop further envenomation). The two pictures below show two other views of the "asp".  The picture FROM THE SIDE (below) shows the asp after I've prodded it a bit, and cause it to pull tight against the wood and arch its body--which elevated its center hairs. The picture FLIPPED OVER (below) shows after I carefully tipped it onto a leaf. This is more for curiosity's sake, rather than identification; since generally, if you see one in this position, you've already been stung, and therefore have a pretty good idea you've encountered an asp.
-------------
                                    WATCH OUT!                                                             FROM THE SIDE                                                             FLIPPED OVER
Here is a short video clip (flv video 622kb) of the puss caterpillar flipping itself rightside up.  Notice the reddish hairs along the center.
I think it's peculiar that these caterpillars are so nondescript in appearance. Generally, extremely venomous animals are brightly colored, to call attention the themselves.  Being easily-recognisable along with painful helps insure that animals able to cause pain in defence are left alone by predators. After a single encounter, most predators would learn to stay away. The "asps", however, seem not to use this strategy. Instead, they seem to be well-camouflaged, and not very obvious. A predator attempting to eat one of these (and I can't imagine one that would; they look like hairballs) would immediately regret doing so. So I'd imagine that most envenomations might be accidental. In that case, the stricken animal wouldn't know what hit it, and wouldn't learn what to avoid.
Yeah, I know...ANOTHER stinging critter that lives down here.  So what? Texas is still a pretty cool state to live in.


Here are some links to more information about these caterpillars. I usually don't do this (link to others' pages), but this is important information. These critters are MEAN! :

Bugs in the News Page, by Jerry Cates

           Go back to my home page, Welcome to rickubis.com
           Go back to the RICKUBISCAM page.
           Go back to the See the World page.