Woolly bear caterpillars are a common sight, particularly in autumn, often sparking curiosity about their fuzzy appearance. Many people wonder if these distinctive creatures are safe to handle, a question that arises from their unique bristly covering.
Understanding Woolly Bear Caterpillars
The woolly bear caterpillar is the larval stage of the Isabella Tiger Moth (Pyrrharctia isabella). These caterpillars are recognized by their dense, fuzzy covering, which typically features black bristles at both ends and a band of rusty orange or reddish-brown bristles in the middle. They can grow up to two inches long and are native to a wide range across the United States, Canada, and Mexico.
Woolly bears are generalist feeders, consuming a variety of low-growing plants like grass, clover, and dandelions. After emerging from their eggs in the fall, they spend the winter as caterpillars, often seeking shelter under leaf litter. In the spring, they become active again, feed briefly, and then pupate inside a cocoon before emerging as the adult Isabella Tiger Moth.
The Nature of Their Bristles
The fuzzy covering on a woolly bear caterpillar consists of stiff hairs called setae. These setae are not venomous and do not sting. Their primary function is defense against predators such as birds and wasps. When disturbed, a woolly bear may curl into a tight ball, presenting its bristles as a protective barrier.
While the bristles are not venomous, they can break off easily upon contact. This mechanical action can cause mild physical irritation, particularly for individuals with sensitive skin. Their pointed nature can lead to a minor, temporary reaction.
Potential Reactions from Contact
Touching a woolly bear caterpillar generally results in no serious harm, but some individuals may experience mild, temporary reactions. Symptoms can include slight itching, redness, or a minor rash. These reactions are due to the caterpillar’s stiff bristles breaking off and lodging in the skin.
Should irritation occur, wash the affected area with soap and water. Applying adhesive tape to the skin and pulling it off can remove embedded bristles. An ice pack may reduce swelling or discomfort, and a baking soda and water paste can alleviate itching.
For persistent symptoms, over-the-counter hydrocortisone cream or an oral antihistamine might provide relief. Medical attention is rarely needed, but should be sought if irritation is severe, persists, or if there is an allergic reaction.
Common Misconceptions
A widespread misconception about woolly bear caterpillars is their supposed ability to predict winter weather. Folklore suggests the width of the caterpillar’s rusty orange band indicates the severity of the upcoming winter: a wider band suggests a milder winter, while more black suggests a harsher one. Some versions of the folklore even suggest that the caterpillar’s 13 body segments correspond to the 13 weeks of winter.
Scientifically, this belief is unfounded. A woolly bear caterpillar’s coloration is influenced by factors like age, feeding duration, and environmental moisture. Older caterpillars, for instance, tend to develop wider brown bands as they molt. The myth gained popularity after an informal 1948 study, but subsequent research has debunked any predictive capabilities.