The Puss Moth, also known as the Southern Flannel Moth, is a fascinating creature with a unique appearance. Its caterpillar stage is widely recognized for its distinctive furry look, resembling a small kitten. While they may appear cuddly, it’s important to know that their appearance is deceiving, as these caterpillars have potent stings.
Puss Caterpillars are primarily found in the Southeast of North America, with their population being most abundant in late spring through early fall. The adult moths, which are small and hairy, have a wingspan of around 1-1.5 inches and display a yellow to orange coloration on their bodies covered with thick hair that looks like fur. This intriguing species offers both captivating features and cautionary tales for those who encounter them.
Puss Moth Overview
The Puss Moth (Cerura vinula) is a species of moth in the Notodontidae family, closely related to butterflies. They have distinct physical features:
- Wingspan: Range between 45 to 70 mm
- Color: White to pale gray with darker markings
Adult moths are nocturnal and have a unique wing pattern that helps them camouflage against tree bark. The larvae, called puss caterpillars, are covered in fine gray or tan hairs, with a teardrop shape and a crest of rusty hairs on their back 1.
Distribution and Habitat
Puss Moths are native to regions in Europe and Asia, and are commonly found in woodland areas, scrubland, and hedgerows. The preferred host plants for their larvae include:
- Willow (Salix spp.)
- Poplar (Populus spp.)
These moths are attracted to light, making them easier to spot in gardens 2.
Regional Distribution Comparisons
Puss Moth Life Cycle
- Laid in batches
- Typically found on plants
Puss moth eggs are laid in batches on plants1. They are the first stage in the life cycle.
- Densely covered with fine gray or tan hairs
- Teardrop-shaped and about 1½ inches long
Cocoon and Pupa
- Tough cocoons
- Remain on plants after adult emergence
Cocoons are tough and may remain on the plant after the adult moth has emerged3. Inside the cocoon, the caterpillar transforms into a pupa, which then transforms into an adult moth.
- Small, hairy moths
- 1-1.5 inch wingspan
Adult moths are small and hairy, with a wingspan of 1-1.5 inches3. Females are larger than males3. The front wings are yellow, while the hind wings are creamy yellow3. Moth bodies are covered with thick hair, which looks like fur and is yellow to orange in color3.
Puss Moth Caterpillars
Puss moth caterpillars, scientifically named Megalopyge opercularis, are known for their unique appearance. They are covered in thick, fluffy setae, reminiscent of a cat’s fur, which gives them their name1. These caterpillars can reach about 1½ inches long, with fine gray or tan hairs that taper to form a tail2.
As far as natural predators for puss moth caterpillars, there is not much information available. However, it can be deduced that they might have various predators, such as birds and predatory insects. Some animals might avoid them due to their stinging setae, which act as a defense mechanism5.
One of the main defenses puss moth caterpillars have against predators is their stinging setae, concealed beneath the longer, softer hairs6. These stinging hairs can cause painful reactions if touched by humans or animals7. Their appearance might also serve as a form of camouflage among foliage, making them less visible to predators8.
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Asp found in Arizona!!!
Subject: Cool bug
Location: Sedona Az
October 6, 2015 1:26 pm
Very cool hairy bug. What is it?
At first we thought this was an Asp, the stinging caterpillar of a Southern Flannel Moth, Megalopyge opercularis, however that species is found in the south from Texas eastward, according to BugGuide. We also learned on BugGuide that there are two related and similar looking species found in Arizona, and we are confident your caterpillar belongs to either Megalopyge bissesa or Megalopyge lapena, and though neither has a common name, and since we suspect that their respective caterpillars are also capable of stinging, we believe Asp is also an appropriate common name for their caterpillars. Of Megalopyge bissesa, BugGuide notes: “The known larval hosts include Quercus oblongifolia (Mexican blue oak) and Arctostaphylos sp. (manzanita).”
Letter 2 – White Asp
Subject: strange catapillar
Location: outside Houston
November 19, 2016 12:36 pm
Attached are a couple pics of a catapillar that I have never seen before outside of Houston, TX. My wife has been bitten/stung by these twice in the last 2 weeks. They are very slow moving. It is a very painful bite/sting that lasts several days and leaves a good size welt. I have lived in this house for 15 years and never seen one. This fall alone I’ve seen about a dozen.
Signature: at your descretion
The Asp is the stinging caterpillar (which you already learned) of the Southern Flannel Moth or Puss Moth. Asps come in a variety of colors, but white Asps do not seem as common as other colors like orange and brown.
Letter 3 – Asp: Caterpillar of the Southern Flannel Moth
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.
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.
Letter 4 – Tabanid Egg Cluster, NOT Asp
Location: Northeast Oklahoma
September 18, 2016 3:58 pm
Found this walking into my house on my front screendoor. The bottom looks like hundreds of tiny legs like fibers
This is an Asp, the stinging Caterpillar of a Puss Moth. Asps should be handled with extreme caution to avoid contact with the stinging hairs. We love your image through the screen which shows the ventral surface.
Karl Provides a Correction: Horse Fly Eggs
The photos provided by Amber are a little fuzzy but this doesn’t look like a caterpillar to me, especially the underside (head, legs and prolegs should be visible). I think this may actually be a Tabanid egg cluster, perhaps ta deer fly. The Bugguide site has an underside photo that looks very similar. Regards Karl
Letter 5 – Asp or Flannel Moth Caterpillar
Subject: Furry Slug Fish
Location: Houston, TX
November 4, 2013 3:56 pm
This furry slug like animal was attached to our trash can outside. Texas (Houston ) Fall early November weather. The animal is about 2” long and about 1/4- 1/2 ” diameter. Furr is a greyish salt an pepper tan color with a tail that is fish shaped but consisting of Furr.
Signature: -stumped in Houston
Hi stumped in Houston,
This stinging Southern Flannel Moth Caterpillar is commonly called an Asp.
Letter 6 – Asp: Southern Flannel Moth Caterpillar
Small, pea-soup green, hairy critter
Thu, Jan 15, 2009 at 2:27 PM
See the photos
Gulf south (USA)
This is a Southern Flannel Moth Caterpillar, Megalopyge opercularis. It is sometimes called an Asp and it stings.
Letter 7 – ASPS
I live in Texas and have always live with (not very well I might add!) what I have always thought were “ASP”. That must not be the “real name” because I can’t find anything on them. They sting like the dickens! Could you please give me more info. on them. They are about an inch long and furry. They tend to hang out on Oak (I think) leaves. THEY STING SOOOO BAD!!!!
Hi Again Julie,
I have finally identified your Asps. It is another name for the Puss Caterpillar. The Puss Caterpillar or “Asp” is the larval form of the Flannel Moth, Megalopyge opercularis. The caterpillars grow to about 1 inch long and are furry in appearance, being completely covered by thick tan to grayish-white hairs that taper toward the back end. Among the long body hairs are shorter spines that discharge venom upon contact. The head and legs are not visible from above. The night-active adults known as flannel moths are rarely encountered. Here is a photo from a great site.
Letter 8 – Asps
Location: Gueydan La. 70542
October 5, 2013 8:03 am
Hello, i found these caterpillars on my back porch in Gueydan La. 70542. on 10/5/2013. They look like they might be a moth caterpillar but i can not find the right I.D. on your sight, i am sure you have it, but i can not find it. You have an awsome site , i have i.d. several bugs and butterflies…. Thank you for your time and effort! I always recommend this site to my freinds and family.
Could you i.d. these caterpillars for me, i will send several pictures to you.
Thanks for your time….
These are Southern Flannel Moth Caterpillars, Megalopyge opercularis, and because they are stinging caterpillars, they are sometimes called Asps, especially in southern states. They are also known as Puss Caterpillars according to BugGuide.
Thank you so much for the quick response and your time, i now have 4 Asps on my back porch..
Thanks for the warning that they sting.
Thank you, Brittany
Letter 9 – Asps
Subject: Asps / Flannel Moth caterpillars…interesting colors
Location: Kyle, Texas
October 29, 2013 10:40 am
Greetings from Kyle, Texas!
This past weekend one of my kids found one of these asps crawling across our porch. It was a buff color and the largest I had ever seen. I captured it in a jar and then gave my kids (and the neighbor kids who were also there) a lesson that these are stinging caterpillars (in the glass jar we could actually see the stingers which are close to the feet) and never to be picked up or played with. We looked it up here at WTB of course, so everybody was well versed on these cute untouchables.
Then, this morning my youngest child who is four, came in saying that he’d found another one and sure enough he had found the darker one on our garage, very close to our rose bushes. On closer inspection, I found the orange one actually on the rose bushes. We decided to remove them and take some photos because of the color variations and also because they are very large…the jar lid they are occupying in the pics are three inches in diameter. To keep them and my kids safe, I put them in our compost pile where I put the other one from Saturday.
Thank you so much for your wonderful site!
Signature: M. family in Kyle
Dear M. family,
Thanks so much for sending us your photo of the color variations in Asps, the stinging caterpillar of the Southern Flannel Moth. We are happy to hear our site was helpful. We are postdating your submission to go live in early November while we are out of the office.
Letter 10 – Mystery Pupa on Asparagus
Any idea what did this?
Location: Ames, IA
September 19, 2011 3:47 pm
Here’s another mystery photo from my cousin in Ames, IA. When I looked at the photo, I couldn’t determine it’s size so couldn’t tell whether it was made by insect or bird. Dinah’s answer is: It was definitely an insect pupae about 1 or 1 1/2 inch long wrapped in an asparagus frond.
I’d very much appreciate it if you could help in any way.
Signature: Thanks, Anna Carreon
This looks like a pupa, probably a Moth Pupa, and it looks nostalgically familiar. Our editorial staff seems to remember seeing this mystery thing in the fields in Ohio, but we need to do additional research. We are going to contact Eric Eaton to see if this looks familiar to him.
Thanks so much for your help. I know you go above and beyond for me and now you’re helping my wonderful Iowa cousins also!
Letter 11 – newly molted Asp
Cocoon popped up found suddenly
Tue, Oct 28, 2008 at 8:24 AM
I was working in my yard and clearing out my shed throwing things away mostly, in a trash can I keep in the backyard. I used the trash can about every 20 mins. One trip to the trash can, there was nothing on the lid of the trash can. On the next trip was this (presumably) cocoon. I lightly touched it and something inside moved once, from left to right. I brought the lid into my garage where I could watch cocoon and protect it from a cold front due in that night.
About 36 hrs later the cocoon (or whatever) moved from it’s original spot and left part of it’s body (?) behind which is shown in the photos.
The insect is about 2 cm long and about 1 cm wide.
Thank you for your time and your website..it’s GREAT
South Central Texas
This is an Asp, a stinging caterpillar of the Puss Moth. It is freshly molted. You are lucky you were not stung as it is reported to be quite painful.