Do Not Touch This Kitty-Like Caterpillar

A puss caterpillar

Although looks as soft as a pussycat, the caterpillar stage of the Southern Flannel Moth (Megalopyge opercularis) is one of the most toxic caterpillars of North America, and the most common caution with this bug is: Don’t Touch!  

The Poisonous Caterpillar

The toxicity of this insect, most commonly called a puss caterpillar, comes from the sharp spines beneath its fur which are attached to poison glands. The stinging hairs are intermixed with soft hairs in scattered tufts.

With even the slightest touch, the urticating (or irritating) spines will break off into a person’s skin injecting the venom beneath.

While some experience only minor pain or burning and itching, severe, long-lasting pain is most common, and some people may even experience vomiting, chest pains, and convulsions. The pain can last up to 12 hours, and little can be done to ease the pain during this time. However if a reaction does become severe or the person has trouble breathing, medical attention should be sought immediately.

Whenever a person is bitten or stung by an insect, it is good to take the insect along to show the physician. However, in this case (and that of any poisonous or otherwise harmful insect), the insect must never be touched, but, if possible picked up with a utensil or tool and placed in a sealed container.

According to the Florida Poison Information Center - Tampa, the first aid that should be applied if a person is stung by a puss caterpillar is:

  • “Place Scotch tape over the affected area and strip off repeatedly to remove spines.
  • Apply ice packs to reduce the stinging sensation, and follow with a paste of baking soda and water.
  • If the victim has a history of hay fever, asthma or allergy, or if allergic reactions develop, contact a physician immediately.”

The caterpillars are most often found on oak, elm, and citrus trees on which they feed; and people working outside around and under these trees are cautioned to be aware, as the caterpillars can fall out of the trees onto workers below. The caterpillars can also be found on other trees and garden plants (e.g., rose bushes and ivy).

Puss Caterpillar Identification

These untouchable puss caterpillars:

  • Are quite attractive with tear-drop shaped furry bodies of about 1 inch in length.
  • Have a stout body that tapers to a tail (making the tear-drop shape)
  • Are completely covered in fur that may range in color from a grayish-white to yellow-brown to dark charcoal gray. They begin as a creamy which and turn darker as they mature.
  • The caterpillar also may have a bright orange line across its body. 

The adult moths:

  • Are about 1 to 1 1/2 inches long.
  • Have wings that are yellow in color with some black fur and white “waves.”
  • Males generally have more black coloring.
  • It is called a “flannel moth” because it's fur-like coating resembles flannel.

Puss Caterpillar Distribution

Although called the “southern” flannel moth, these insects (and their larval puss caterpillar stage) can be found along the U.S. east coast from as far north as New Jersey down to Florida. From Florida, where it is very common, it is then found along the south/southwest—across to Arkansas and Texas—where it is abundant in the western half of the state. There have been years in the past in which the number of caterpillars became so overwhelming in the Texas cities of San Antonio and Galvestono that schools were temporarily closed to stop the stinging of the children. An adult, the moth is completely harmless.