Human poisoning by Lepidoptera (butterflies, caterpillars and moths) has been 
known to physicians since old times. In the last few years, several factors have 
been causative of a great number of contacts between different stages of these 
insects and humans, occasionally with epidemic features. Species of medical 
interest in Argentina are those related to Megalopygidae, Saturniidae, 
Hemileucidae, Arctiidae, Notodentidae and Eucliedae families. Among all the 
species involved, it is important to describe the pathology produced by contact 
with Lonomia obliqua caterpillar (Saturniidae). The caterpillar Lonomia has 
several enzymes with procoagulant and fibrinolytic activities, acting on various 
components of the hemostatic system inducing hemorrhage that can lead to death. 
In the South of Brazil during the last years caterpillars of this butterfly 
caused a great number of cases of erucism including some deaths. In the past two 
years, there have been some cases of poisoning by Lonomia obliqua in Misiones, 
in the North East of Argentina on the border with Southern Brazil. This presents 
a potential risk, taking into account the poor knowledge regarding this insect 
and its venom in Argentina. This brief actualization gives some biochemical, 
clinical and epidemiologic tools towards understanding human Lepidopterism, an 
uncommon medical problem in this country.