Toxicological Trivia from April 13, 2010: Hylesia is a genus of butterfly that causes persistent dermatitis due to contact with the adult hair. There have been outbreaks of different species in Mexico, French Guyana, Venezuela, Brazil, Peru, Argentina and Uruguay. In Argentina,the epidemic episodes occurred in the provinces of Misiones, Entre Rios and Buenos Aires. Hylesia Nigricans was declared a national plague of agriculture. due to its larvae, which feeds on leaves: a) In 1911; b) In 1931; c) In 1951.