Meet the Brown-tail Moth (Euproctis chrysorrhoea)

Cicely Blair wrote a paper about the rash caused by the brown-tail moth caterpillar in the British Isles.[16] It, and other descriptions, confirmed that loose hairs can break off and cause very itchy rashes on contact with skin, as well as breathing difficulties similar to asthma if inhaled. Rashes can persist for weeks.[6][7][17][18] The same symptoms have been reported as far back as 1903.[1] The reactions are due to a combination of mechanical and chemical stimuli, the barbed hairs in effect becoming lodged in and physically irritating the skin, and also functioning as microtubules to introduce irritating chemical compounds that have hydrolase, esterase and hemolytic activity.[6][7] This rash reaction may be referred to as lepidopterism. The species should be handled using protective gloves at all stages of its life cycle. Shed hairs blow about, and can be brought indoors on clothing and shoes, so rashes can occur without the victim coming in direct contact with the caterpillars. The toxins in the hairs remain potent for up to three years after being shed. Outdoor activities such as mowing a lawn or raking leaves in the fall can cause exposure.[3][5]