The Giant Leopard Moth caterpillar (Hypercompe scribonia) is a striking insect often encountered in gardens and forests across North America. Its large size and dense, jet-black coat of bristles make it highly recognizable, sometimes leading to comparison with the smaller “woolly bear” caterpillars. This dramatic appearance frequently prompts questions about its safety and whether this common species poses any danger to humans.
Identification of the Giant Leopard Moth Caterpillar
The Hypercompe scribonia caterpillar is characterized by its deep, uniform black coloring and substantial size, reaching up to three inches in length when fully grown. Its body is covered in thick, stiff bundles of shiny black hair, called setae, giving it a fuzzy appearance. When disturbed, the caterpillar rolls into a tight ball, exposing bright reddish-orange bands between its segments. This flash of color, contrasting with the black setae, serves as a warning signal to potential predators. It is an opportunistic feeder, consuming a wide variety of broad-leafed plants, including dandelions, violets, and various tree leaves, and is often active in the fall before overwintering.
Chemical Safety: Are They Poisonous?
Despite its formidable appearance, the Giant Leopard Moth caterpillar is not chemically poisonous or venomous. A poisonous organism contains a toxin harmful when ingested, while a venomous one actively injects a toxin. The Hypercompe scribonia caterpillar lacks the specialized glands and delivery systems for either strategy. It does not secrete harmful toxins through its bristles or skin. Therefore, contact or accidental ingestion would not result in systemic poisoning. Like other non-toxic “woolly bear” type caterpillars, it relies on physical defenses rather than chemical warfare.
Understanding the Bristles and Physical Irritation
The main concern regarding this caterpillar stems from its dense coat of setae, which serve as a physical defense against predators. These hairs are stiff and sharp enough to cause mechanical irritation upon contact, but they are not designed to inject toxins. Handling the caterpillar can result in a mild, localized reaction, such as temporary redness, itching, or a prickling sensation, particularly on sensitive skin or in individuals prone to allergies.
The setae can embed themselves lightly into the skin, causing discomfort similar to a mild splinter. These bristles are classified as non-urticating, meaning they do not easily break off and release an irritating substance like the true stinging hairs of other caterpillar species. If contact occurs, the mild reaction is usually a result of physical penetration rather than a toxic or allergic response. To mitigate irritation, gently remove any remaining hairs using adhesive tape. The area should then be washed with soap and water. Applying a cool compress or a mild hydrocortisone cream can help soothe localized itching and redness.
The Adult Giant Leopard Moth
Following the larval stage, the caterpillar pupates, often forming a thin, net-like cocoon in a sheltered location. The resulting adult is the Giant Leopard Moth, a visually striking member of the tiger moth subfamily. The adult moth is large, with a wingspan ranging from 2.25 to 3.6 inches. Its wings are brilliant white, covered in a pattern of bold black spots, some of which are solid or appear iridescent blue.
When the moth is at rest, the striking colors of its abdomen are often concealed. These colors include dark blue-black markings and bright orange lateral areas. The adult moths are strictly nocturnal and are frequently spotted near outdoor lights during the warmer months. Unlike the caterpillar, the adult moth relies on its striking coloration and nocturnal habits for survival, having no physical defense mechanism involving bristles.