Not Found

Find information on medical topics, symptoms, drugs, procedures, news and more, written in everyday language.

* This is the Consumer Version. *

Puss Moth Caterpillar Stings

(Asp Stings)

By Robert A. Barish, MD, MBA, Professor of Emergency Medicine and Vice Chancellor for Health Affairs, University of Illinois at Chicago ; Thomas Arnold, MD, Professor and Chairman, Department of Emergency Medicine, LSU Health Sciences Center Shreveport

The venomous puss moth caterpillar (Megalopyge opercularis; also called the asp) is present in the southern United States. It is teardrop shaped and has long silky hair, making it resemble a tuft of cotton or fur.

When a puss moth caterpillar rubs or is pressed against a person’s skin, its venomous hairs are embedded, usually causing severe burning and a rash. Pain usually subsides in about an hour.

Occasionally, the reaction is more severe, causing swelling, nausea, and difficulty breathing.


  • Relief of pain

Several techniques may soothe the pain and burning caused by puss moth caterpillar stings.

  • Washing the sting with soap and water and using a hair dryer set on low to dry the area

  • Putting tape on the site and pulling it off to remove embedded hairs to prevent further injury

  • Applying isopropyl alcohol (rubbing alcohol) to the sting

  • Applying a baking soda slurry

  • Applying calamine lotion

  • Placing an ice pack or an ice cube wrapped in plastic and a thin cloth over the sting

More severe reactions require immediate medical attention.

* This is the Consumer Version. *