 These caterpillars are about 4.5 to 5.5 centimeters (about 2 in) long, with background colors ranging from green to brown.Well camouflaged, they have rows of tubercles crowned with whorls of easily detachable spines of different sizes.Caterpillars of many species can cause irritation by their hollow body hairs that envenom or detach easily, or can be poisonous if ingested; however, prior to investigations into "Lonomia" caterpillars, it was not known that caterpillars could produce toxins which in sufficient quantities could kill a human being.