Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Puss Moth Caterpillar Stings

(Asp Stings)

By

Robert A. Barish

, MD, MBA, University of Illinois at Chicago;


Thomas Arnold

, MD, Department of Emergency Medicine, LSU Health Sciences Center Shreveport

Last full review/revision May 2020| Content last modified May 2020
Click here for the Professional Version

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.

Treatment of Puss Moth Caterpillar Stings

  • 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.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version

Test your knowledge

HIp Fractures
The hip joint consists of several areas: the pelvis, then the round upper end (head) of the thighbone (femur), then the area below the head of the femur (also called the neck of the femur), and then two large bumps beneath the neck of the femur (also called trochanters). Most hip fractures occur in which of the following areas of the hip? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
TOP