What's That Bug? does not endorse extermination

Subject: ugly, painful rash from a cocoon
Location: Nitro, WV
November 14, 2012 11:55 am
Two nights ago i tried on an old pair of pants that i kept in my basement closet. when i put them on i felt sting in my thigh that felt like a splinter and as i walked toward my mirror i felt a whole bunch of those stings so i ripped the pants off thinking there were bees in my pants or something. I immediately had a burning itchy rash all over my thigh. i looked in my pants to see if there were any bugs but all i noticed was group of small fibers that i thought maybe somehow my cat brought in stinging nettle hairs. Then this morning i noticed the cocoon in the floor where i tried the pants and realized that is what it was. I still have a rash 2 days later and its miserably itchy. I am curious to know what the cocoon is and how to make sure i get this insect far away from my house. Thank!
Signature: Lisa [Ed. Note:  Name withheld upon request]

Possibly Arctiid Cocoon

Dear Lisa,
Our first instinct is that this is the Cocoon of a Tiger Moth in the subfamily Arctiinae.  We didn’t search for an exact match, and though the color is wrong, this image from BugGuide shows the general form or cocoons in the subfamily.  We didn’t realize that Woolly Bears as the Arctiinae caterpillars are commonly called, had utricating hairs.  We have not noticed Woolly Bears in lists of stinging caterpillars we have linked to in the past.  The Ark in Space website is especially nice.  We wondered if perhaps this might be the cocoon of an Asp, but this image from BugGuidelooks very different.

Rash caused by Caterpillar Hairs

We will continue to research this matter to see if we can learn anything about the identity of the cocoon that gave you a rash.

Utricating Hairs


What's That Bug? does not endorse extermination
Location: West Virginia
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6 Responses to Caterpillar Hairs produce human rash!!!

  1. Eric Burns says:

    I had exactly the same thing happen to me two days ago in the Snowy Mountains, Australia. The picture of the Arctiid Cacoon looks exactly like what fell out of my jacket sleeve.

  2. Satria Perdana says:

    I had this happen yesterday, I accidentally stepped on it inside my left shoe it was so itchy in all over my left foot and leg till now , the spines struck all over my foot i can’t remove it because its too deep.
    Please reply this comment and give any information to handle this, will my foot be okay if i don’t remove the spines? Will it be removed by the body by time? Thank you

  3. ROBERT DUPUIS says:

    I was cutting a nearly dead Popular tree down in my front yard in late Dec. (Quabbin Reservoir region of central MA) The days were warm but the night were below 32F. After dropping the tree I noticed rash on the inside of my wrist just above my palm (near all those veins you can see) Within an hour, my wrist swelled to the point of limited movement and the rash became very high in shape. It’s shape was that of a cocoon or a caterpillar body and there were a great deal (100 or so) small red prick marks surrounding the worm like rash all around it. I went inside and washed it and put some witch hazel on it and then slowly over 36 hours it mostly went away. Since then, I thought I had the flu,,,,recognizing my symptoms 3 weeks later are spot on to what I have read about the PERNICIOUS PUSS stings (not saying it was this insect yet the symptoms do match). headaches, nausea, vomiting, intense abdominal distress, lymphadenopathy, lymphadenitis. I’ve had all of this without a fever. I’m feeling better slowly yet there was a point that I could not even speak, I thought I had Laryngitis….horrible swelling of all of the glands in my neck, lasted about 4 days, started out a day or so after the bite and grew to extreme discomfort after 4 days….. NOt sure if there is any treatment this late in the game yet i’m heading to the doctor

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