Close-up of a hickory tussock caterpillar featuring predominantly gray coloring complemented by white hairs protruding from its body, creating a fuzzy appearance. Notable are two distinct black tufts, one located towards the front and the other towards the rear, set against a medium brown background. Earth hosts a vast array of caterpillar species, exceeding 20,000 in number and found across the globe with the exception of Antarctica. While many are harmless, certain species possess venomous properties akin to snakes, with defenses extending beyond irritating hairs to include toxins capable of causing severe, and at times fatal, side effects. Some of these species inhabit the United States, and encounters may occur unknowingly.
Giant Silk Moth Caterpillar, Lonomia obliqua, a member of the Saturniidae or “giant silk moth” family, distinguishes itself as one of the most lethal caterpillars globally during its larval stage, contrasting with its benign adult moth form. Recognizable by the tubercles covering its body, topped with detachable spines that are released when the caterpillar feels threatened, its coloring varies from striped browns to greens, aiding in its camouflage within South American forests. This two-inch-long caterpillar inflicts significant pain and is responsible for numerous deaths annually, known locally as the “Killer Brazilian Caterpillar” or the “Assassin Caterpillar.” The toxin it releases through its spines acts as a hypodermic needle, containing an anticoagulant leading to internal bleeding, disseminated intravascular coagulation, and hemorrhaging within the human body.
Bag Shelter Caterpillar, Ochrogaster lunifer, belonging to the Thaumetopoeidae family and native to Australia, may appear innocuous with its fluffy exterior but is covered in numerous irritating hairs. Also known as the “itchy grub” and processionary caterpillar, these urticating hairs detach easily, causing airborne irritation even without direct contact. Identified by their black bodies and lengthy, distinctive hairs, these caterpillars can induce severe itchiness lasting days and contain an anticoagulant toxin that can lead to complications if ingested or inhaled.
Spiny Oak Slug Moth Caterpillar, like many insect species, showcases vibrant colors and intricate patterns.
Warning: The spiny oak slug moth caterpillar, also known as Euclea delphinii, is a member of the Limacodidae moth family and can be found in the Eastern and Southern U.S., as well as Central and South America. This caterpillar thrives in heavily wooded areas, particularly on oak and hardwood trees during the summer and fall months. It stands out due to its vibrant neon coloring of green, orange, yellow, and red. Like the giant silk moth, the spiny oak slug moth caterpillar possesses tubercles with toxin-filled spines.
This caterpillar may cause mild irritation or more severe reactions when its spines release a toxin upon contact. The toxin can lead to allergic reactions in rare cases. Symptoms may include burning, stinging, swelling, nausea, and other effects that can manifest immediately or within hours of contact.
Similarly, the saddleback caterpillar, known as Acharia stimulea, is another member of the Limacodidae family found in Eastern North America and parts of Mexico. Recognizable by its brown body with a neon green “saddle” and spines, this small caterpillar can cause intense pain, swelling, and other reactions due to its toxin-filled spines. Immediate effects may include pain, swelling, and in rare cases, anaphylactic shock.
The io moth caterpillar, found throughout North America, is another species to be cautious of due to its toxic spines. These bright green caterpillars have brown and cream-colored stripes and can cause similar reactions to bee stings upon contact. While generally not life-threatening, the venom may lead to allergic reactions in some individuals.
Lastly, the southern flannel moth caterpillar, also known as Megalopyge opercularis, is a venomous species found in the southeastern U.S., particularly in Florida. These caterpillars can be encountered as far north as New Jersey and eastern Pennsylvania, and their toxic spines can cause severe reactions in some individuals. It is essential to exercise caution and avoid contact with these caterpillars to prevent potential allergic reactions or other adverse effects.
Various trees such as oaks, elms, maples, hollies, sycamores, hackberries, and certain shrubs are home to these dangerous caterpillars, which can pose a threat to humans due to their close proximity. The southern flannel moth caterpillar, though deceptively harmless-looking, harbors venomous spines beneath its fuzzy exterior, making accidental contact a painful experience. Similarly, the hag moth caterpillar, also known as the “monkey slug,” is equipped with stinging hairs and tentacle-like limbs for defense, presenting a challenge to those who may encounter it in wooded areas. Lastly, the hickory tussock caterpillar, with its beautiful yet deceiving appearance, packs a potent sting that can result in dermatitis and allergic reactions if not treated promptly. It’s essential to exercise caution and avoid contact with these caterpillars to prevent potential harm.
