Caterpillars or larvae forms of nocturnal butterflies are important from the medical and toxinologic point of view. Lesions caused by contact with these caterpillars are called «erucism», such as the hemorrhagic injuries caused by the Lonomia species. In 1967, the first case of hemorrhagic syndrome associated with Lonomia was reported in Venezuela; and there have been more than 2000 cases reported in South America since then. In Colombia, the presence of Lonomia species was described, and in 2000, the first two cases of hemorrhagic syndrome were reported in Casanare. Pathogenicity of these insects is due to a tegument with multiple tubular bristles, containing venom which is released after the skin contact with the bristles. After the contact, local and hemorrhagic manifestations appear in 50% of the patients. Treatment of this type of poisoning includes local measures and the rapid administration of the specific antivenom. Therefore, it is important to consider the presence of this type of insects in certain territories of the country and report suspicious cases.