The “asp” is not a snake, but rather a caterpillar. More formally called the puss caterpillar or southern flannel moth caterpillar (Megalopyge opercularis), this larval stage of a moth can cause considerable discomfort upon contact. Its appearance can be deceiving, leading many to underestimate its potent defense.
Identifying the Asp Caterpillar
The asp caterpillar possesses a distinct teardrop shape and is covered in long, silky hairs that give it the appearance of a tuft of cotton or fur. Its coloration varies, commonly ranging from yellow or gray to reddish-brown, or a mixture of these hues. These caterpillars typically measure between 1 to 1.5 inches in length. Its soft fur conceals dense, venomous spines.
These caterpillars are most commonly found in the southern United States, inhabiting shade trees and shrubbery around homes, schools, and parks. They typically have two generations per year, with peak activity observed in late spring and late fall.
Appearance of the Sting Mark
An encounter with an asp caterpillar results in immediate and intense throbbing pain. The sting site often develops a rash with red spots, which may evolve within a few hours into a grid-like or linear pattern of raised red bumps or welts. Small white or red dots might be visible within the welts, indicating the points where the spines penetrated. The surrounding skin typically becomes noticeably red and inflamed. The appearance can vary slightly depending on skin tone and the extent of contact.
Associated Symptoms and Progression
Beyond the visible mark, the sting inflicts an intense, burning, and throbbing pain, which many describe as excruciating. Along with severe pain, common symptoms include swelling, itching, and widespread redness at the sting site. In more susceptible individuals or severe cases, systemic reactions can occur, such as nausea, vomiting, headache, muscle cramps, fever, swollen glands (lymphadenopathy), and even shock or respiratory distress. The pain from the sting generally begins to subside within an hour, and the visible red spots may disappear within a day or two, though symptoms can persist longer.
What to Do After an Asp Sting
Immediate action after an asp sting involves removing any embedded venomous spines. This can be done by repeatedly applying and stripping off adhesive tape from the affected area. After spine removal, gently wash the sting site with soap and water to clean the area and reduce the risk of infection. Applying an ice pack or cold compress to the sting can help alleviate pain and swelling.
Over-the-counter pain relievers, such as acetaminophen or ibuprofen, can be taken to manage discomfort, and oral antihistamines may help control itching. Applying a baking soda slurry or calamine lotion can also provide soothing relief.
It is important to seek medical attention if severe symptoms develop, such as difficulty breathing, widespread hives, or swelling of the face or throat, as these could indicate an allergic reaction. Medical consultation is also advised if the sting is near the eyes or mouth, if pain is unmanageable, or if symptoms worsen or persist for an extended period. Avoid squeezing the sting site, as this can release more venom.