Exterminating Puss Caterpillars 11

— This article by Jerry Cates, first published on 2 March 2010, was last revised on 22 January 2014. © Bugsinthenews Vol. 11:03(07).


The following is a step-by-step approach that the author has used and supervised. It should be followed in the sequence prescribed.

1. First, protect yourself and others.

On discovering a puss caterpillar infestation, insure that you, your family, and others stay out of the area to avoid getting stung, until you are properly dressed and have appropriate treatment equipment with you.

Puss caterpillars may drop out of trees, unnoticed, onto clothing. A puss caterpillar down a blouse or tee-shirt always ends badly. Enter infested areas wearing a wide-brimmed hat, a shirt or blouse buttoned at the neck, and heavy rubber gloves. Inspect clothing often; remove caterpillars from your clothing with a gloved hand, placing them in a container of soapy water.

These caterpillars, at maturity, leave their feeding places in trees and shrubs to find another place to spin a cocoon. In their travels they may be found anywhere in the infested area. Do not pick up anything, lean against anything, or sit down on anything without first inspecting every surface of that thing to insure no caterpillars are there.

2. Cordon off the area.

After inspecting the area to determine where caterpillars are actively feeding, cordon off the area. Suggestion: place yellow CAUTION tape, available at most hardware stores, around affected shrubs and trees. Most puss caterpillar infestations involve only a few trees or shrubs, so the cordoned area will be small.

At a municipal or private park, at a commercial establishment, or at your place of work, where you may not have authority to take such action, contact the managment, first by phone, next by email, to insure a written message is documented. Formally request that the affected area be cordoned off. In your email, link to this webpage so that the authority you communicate with can be brought up to speed on this caterpillar quickly, so that corrective steps will be taken.

Once a treatment method is selected, inspect daily for more caterpillars until several days pass without any being seen. Only then should the CAUTION tape be removed.

3. Decide on a Treatment Strategy.

In theory, these pests can be controlled using ordinary commercial pesticides labeled for caterpillar control. If you choose to use traditional pest management methods, select a commercial pesticide that is labeled specifically for puss caterpillars. However, please read the following first:

Neither traditional chemical or biological pesticide applications are effective at controlling puss caterpillars. Strong evidence indicates that traditional pesticides — as well as biologicals such as Bacillus thuringiensis — potentially lead to more serious puss caterpillar infestations, later, at the treatment site. Why? Because the most effective exterminator of the puss caterpillar is the tachinid fly, and traditional and biological pesticides kill tachinid flies more efficiently than they kill puss caterpillars. As a result, following applications of traditional or biological pesticides, enough puss caterpillars survive to mount a strong follow-up infestation, and because the pesticides killed their natural tachinid fly predators, the latter have been rendered unable to control them naturally. For details on research conducted on the natural predators of the puss caterpillar, click on this link.

4. Using Manual Methods.

Manual methods, where the caterpillars are removed using tongs or a gloved hand, can work well, especially when only a few caterpillars are visible and the number of infested bushes is small. For example, in the coffee plantations of Central America, where chemical pesticides would contaminate the coffee beans, such chemicals must be avoided entirely. Yet, I am told that plantation workers sometimes find a small number of puss caterpillars on a few of the coffee trees on the plantation while harvesting the coffee beans. The workers deal with these manually, by shaking them loose and stamping them on the ground, or by picking the caterpillars off, often using a bare hand (not recommended!)

To manually remove the caterpillars from an infested shrub or tree, grasp them with tongs or a gloved hand (heavy rubber gloves are best). Drop each caterpillar into a container of soapy water. A capful of liquid dishwashing detergent in a gallon of warm or hot water produces a solution that immobilizes the caterpillar to prevent it from crawling out of the container, and kills within minutes. Afterward, flush the solution and its load of caterpillars down the drain, then wrap and discard or wash the container thoroughly, and be sure to wash off your gloves before attempting to remove them.

5. Augmenting Manual Extermination Methods.

An alternative, or addition, to the manual method described on the previous page, is to use a squeeze bottle or syringe to apply natural pesticides such as cedar oil, orange oil, rosemary oil, or similar pesticides to the caterpillars you find.

When using natural pesticides, you are less likely to come into direct contact with the puss caterpillars, yet you will still manage to kill them in such a way that their natural predators are not affected.

Since you won’t find every caterpillar, the ones that are left must still be killed by natural predators, so keeping those predators alive is very important. Please, if you have experience using natural pesticides against puss caterpillars, contact Jerry with that information (see contact link at bottom of page, or leave a comment in the space provided) so that information can be posted here for others to read.

If your site has a major infestation of puss caterpillars, or if they are infesting the foliage of several tall trees on your property, is is likely that someone or something destroyed their natural predators during the previous 12 months.

The temptation to spray infested shrubs or trees with traditional pesticides will be very strong, yet that will only compound the situation. Spraying traditional, or even biological pesticides will likely lead to a repetition of the infestation cycle for several more years. The caterpillar’s natural predators must be allowed to recover, so they can destroy the puss caterpillars without any additional help.

Please contact Jerry (see contact link at bottom of page, or leave a comment in the space provided) with information on such infestations, along with details of any unusual events in your neighborhood that may have contributed to it.

If you have experiences using traditional pesticides, THURICIDE, DIPEL 150, or any other agent or product for puss caterpillar control, please contact me with a report on your experience.  It is important to learn from the experiences of others, and your reports will help immeasurably.  Many thanks in advance. Note that I have posted this request on the bugsinthenews websites since 2002, and have yet to receive a positive report involving the use of traditional commercial pesticides or biologicals…


Links:   (1) Puss Caterpillar General Information.    (2) The Puss Caterpillar’s Stinging Apparatus. (3) Puss Caterpillar Extermination. (4) The Puss Caterpillar’s Natural Predators. (5). Puss Caterpillar Stings–Medical Interventions. (6) Puss Caterpillar Stings–Home Remedy First Aid Measures.



  • Kingdom Animalia (ahn-uh-MAYHL-yuh)  — first described in 1758 by the Swedish taxonomist Carolus Linnaeus (1707 – 1778), using the Latin word animal = “a living being,” from the Latin word anima = “vital breath”, to refer to multicellular, eukaryotic organisms whose body plans become fixed during development, some of which undergo additional processes of metamorphosis later in their lives; most of which are motile, and thus exhibit spontaneous and independent movements; and all of whom are heterotrophs that feed by ingesting other organisms or their products;
  • Phylum Arthropoda (ahr-THROPP-uh-duh) first described in 1829 by the French zoologist Pierre André Latreille [November 20, 1762 – February 6, 1833], using the two Greek roots αρθρον (AR-thrawn) = jointed + ποδ (pawd) = foot, in an obvious reference to animals with jointed feet, but in the more narrow context of the invertebrates, which have segmented bodies as well as jointed appendages;
  • Class Insecta (ehn-SEK-tuh) — first described in 1758 by the Swedish taxonomist Carolus Linnaeus (1707 – 1778), using the Latin word insectum, a calque of the Greek word ἔντομον ( EN-toh-mawn) = “(that which is) cut into sections”; comprised of arthropods with chitinous external (exo-) skeletons, a three part body composed of a distinct head, thorax, and abdomen, the midmost part having three pairs of jointed legs, and the foremost part having a pair of compound eyes and antennae;
  • Subclass Pterygota (tare-ee-GOH-tah) — first described in 1888 by Lang, using the Greek roots πτερυξ (TARE-oos) = wing, to refer to insects with wings, or that had wings but in the process of evolution have since lost them;
  • Infraclass Neoptera (nee-OPP-tur-uh) — first described in 1890 by the Dutch entomologist Frederick Maurits van der Wulp (1818-1899) using the Greek roots νεος (NEE-ose) = youthful, new + πτερυ (TARE-ohn) = wing, to refer to winged insects that are capable of folding their wings over their abdomens, in contrast to more primitive winged insects that are unable to flex their wings in this manner (e.g., the dragonflies, in the infraclass Paleoptera);
  • Superorder Endopterygota (ehn-doh-tare-ee-GOH-tah) — first described by the English physician and entomologist David Sharp (1840-1922) using the Greek root ενδον (ENN-dohn) = within + the established expression pterygota (see above) to refer to insects within the latter subclass that undergo complete metamorphosis, i.e., larval, pupal, and adult stages;
  • Order Lepidoptera (lep-uh-DOPP-tur-uh) — first formally described in 1758 (though he coined the expression in 1735, informally) by the Swedish taxonomist Carolus Linnaeus (1707 – 1778), using the Greek roots λεπιδωτος (lepp-eh-DOH-tose) = scaly + πτερυ (TARE-ohn) = wing, to refer to insects with scales covering their wings, i.e., the moths and butterflies;
  • Family Megalopygidae (megg-uh-low-PIDGE-uh-dee) —  from the Greek root μεγας (MEG-as) = great, vast, large + the Greek root πυγη (PIDGE-ee) = rump, tail + the Greek patronymic suffix -ιδες (eye-DEES) commonly used in zoological taxonomy to indicate a family name, in reference to a family of moths typically having an exaggerated tail, honoring the fact that these caterpillars often–but not always–trail a conspicuous tail of hairs; this family is presently represented by 23 recognized genera that are found in North America and in the New World Tropics; in North America as many as 44 species have been described, some of which may be synonyms, but all of which are known, while in the larval (caterpillar) stage, to produce extremely painful stings in humans who come into contact with them;




— Questions? Corrections? Comments? BUG ME RIGHT NOW! Telephone  Jerry directly at 512-331-1111, or e-mail jerry.cates@entomobiotics.com. You may also leave a comment in the space provided below.

11 thoughts on “Exterminating Puss Caterpillars

  1. Robert Williams Jun 5,2010 2:23 pm

    I was the childhood victim of an asp (puss caterpillar) sting. Memory of it has remained with me for more than 60 years. It would be productive to publish a photo of the puss moth on your website. If you see the moth the caterpillars have been there.


    Editor’s Note: Excellent idea. In fact, the research project I carried out in the fall of 2009 yielded a large number of moths which are ready to be photographed. I plan to take photos of the moths and the eggs they laid very soon. Thanks for the reminder.


  2. Kimberly Jun 16,2010 6:42 pm

    I have a sycamore tree next to my house that I suspect has been infested for years. It is very large, and we are looking into having it cut down. I also found at the other end of my yard, my young blueberry bush covered in smaller ones. I assume they just hatched. I’m not sure what to do. We killed them by cutting them off the bush with scissors and then cutting them in half. I worry as I have two young boys. We live in Louisiana too. What should we do? Please email me a response. I have no clue what the eggs look like or what the moths look like or I’d destroy them too. Luckily we haven’t been stung yet, and I’d like to keep it that way. Is this going to keep happening year after year? Where can I get those flies if so?



    Chances are, because your caterpillars are feeding on sycamore trees, they are not puss caterpillars but are, instead larvae of the sycamore tussock moth (Halysidota harrisii Walsh). Take some digital photos of several of them, closeup, and send them to jerry.cates@entomobiotics.com as email attachments (full resolution works best) and I will do my best to identify them for you.

    The sycamore tussoc moth caterpillar is not famous for its sting, so I don’t think you have to worry about it the way you would if it was a puss caterpillar. As with the puss caterpillar, natural predators–probably the same tachinid flies that attach puss caterpillars–are most effective at keeping infestations in check. And, fortunately, you don’t need to go buy some of those tachinid flies; they come free, courtesy of Mother Nature.


    Kimberly replied on 06.17.10:

    I’m pretty sure they are the puss caterpillar, but let me know what you think from these pictures. I could be mistaken that they are feeding on our large tree. They seem to have come from that area last year though. All around it we would find them…… on the fence, the trash cans, the walls, the sidewalks. Tons of them! I have killed at least 15 on this little blueberry bush. We have only lived here a year, but it was around this time last year that we noticed them. They’re back! So, let me know what you think.

    Thank you very much for your time,

    After examining Kimberly’s photos, I am forced to conclude that these are, indeed, puss caterpillars. I will post the photos on another page soon. In the meantime, my advice to Kimberly is to let the caterpillar’s natural predators resolve the infestation for her. That is not easy to do, because we have been taught, all our lives, that chemistry trumps nature in all things. That is not the case here, though. No pesticides made by man can compete with the natural predators of the puss caterpillars, yet most pesticides are capable of killing those natural predators with great efficiency.


  3. Donna Morgan Jul 1,2010 10:10 am

    Yes, I too was stung by one of these creepy critters. It was on the arm of an outside chair and I did not see it. I sat down and placed my forearm on the arm of the chair…. OUCH within seconds. Big, bad, hot sting.

    Our back porch, gutters,concrete,etc. are very infested with these things. At the moment, I have someone out there attempting to pick them off and into the soapy water as suggested.

    Would there be an “origination” area?

    What are “natural predators?”

    Thanks for any help – your site is extremely helpful…


    Editor’s Note: Regarding your questions–I address most of them in an article on The Puss Caterpillar’s Natural Predators. Click on that link and, after reading it, let me know of any questions you might have.


  4. Jess Pettit Jul 18,2013 11:46 pm

    Several members of my family, including me, have been stung by the puss asp, Megalopyge opercularis. The caterpillar looked like a tuft of gray wool carpeting with a short tail tapering from the body.

    The stings occurred in the Lower Rio Grande Valley of Texas. They were excruciating painful with extreme burning pain lasting for 8 hours and residual symptoms lasting for days. Venomous hairs in a distinct grid pattern are thought to be on the underside near the feet, rather than the top or back of the caterpillar. Erythematous (blood-colored) spots or flecks appear at the site of the sting and remain for weeks. The sting can leave a scar in the distinctive pattern in roughly the position of the feet and outline of the caterpillar.

    I have also seen one asp in 35 years in Dallas, TX and several at Camp Classen in Davis, OK. If stung, I would suggest the victim seek medical treatment and be observed until the symptoms disappear in case of a severe reaction.

  5. Page Sep 10,2013 8:22 am

    A puss caterpillar dropped on my back while I was sitting under an oak tree in Okeechobee FL. I had to rip my shirt off, flick this now ugly blob off it and then I used the shirt to rub my back. I had all the bad reactions that I am now reading about.

    I went back to the property and saw a puss caterpillar and figured out what got me. This is the first time I have seen these in 5 years of owning this land. I understand what these are but how long will these be around? They will turn into moths soon I hope.
    We have horses, do you think these can affect these animals?


  6. April Sep 25,2013 1:37 am

    I also was stung by one almost a month ago. Every sience I was stung I have been itching a lot! All over my body. First thing I thought was I had gotten into some posion oak or something. Two weeks later I’m still itching like crazy. Big wealps will appear where ever I’m itching/burning at the time! Yesterday right in the same spot on my hand I got stung little bumps popped up and they itch sooo Bad!! Any idea what’s going on? I am miserable and im willing to try anything at this point in time.
    Thanks April

  7. Angie Oct 5,2013 9:47 am

    I saw a puss caterpillar for the first time in my life 2 days ago (I’m almost 39 yrs old). It was crawling up the wall near my front door. The next day my daughter saw one on our balcony. There’s a huge tree (Oak, I think) right in front of our apartment, with branches dangling over the building & our staircase. Luckily we have not been stung. As soon as I found out what it was, I exterminated it. I’m curious as to the experience of others with Thuricide. I want to treat, or form a barrier, if I could, with a pesticide that works. I want to treat my balcony & front door area. Will this even work?

  8. Brenda Nov 17,2013 5:35 pm

    I have a large infestation of puss caterpillars on my back porch. I have inspected my trees, and found none. There are no plants on the porch. what could they be feeding on to be there. The porch is brick and pebble/concrete. They are on the ground as well as on the plastic chairs. I have killed 5 today alone. What should I do?

  9. Chris Jun 22,2014 11:42 am

    Stumbled onto your site looking for how to exterminate these. Just discovered them on a young flowering pear tree near Austin, TX while trying to figure out why all the leaves were dying. Odd little critter. Thankfully I didn’t pick them off by hand…

  10. Nitza Sep 12,2014 8:44 am

    Last year I found those creepy creatures all over my backyard. Don’t knowing what they were I contacted an exterminating guy who end up don’t knowing what they were. I saw that every day they were more and more at the point that they were infesting my backyard. I did not know (until today) that they are dangerous. I took them off with my water hose and problem solved. This year, just today I found out that they are coming back. I just want to know what to do to get rid of them. I have kids in the house and I don’t want to have any disgusting situation with these creepy creatures and my kids.

    Please let me know how I can get rid of this. Don’t tell me to do it manual because my house walls are so high. Help!

  11. admin Dec 13,2014 11:29 am

    Nitza: if the puss caterpillars recur in a particular location it is usually because the soil under the botanicals they infest has been treated with a pesticide that prevents tachinid flies, their natural predators, from developing to adults there. Once tachinids begin to multiply in response to a puss caterpillar infestation the infestation is doomed, as every caterpillar becomes parasitized and dies.

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