Lonomia obliqua Walker (Lepidoptera, Saturniidae) has urticant spines in larval stages. This species may cause death as a result of haemorrhages caused by a toxin released from the caterpillar's spines onto the skin of the victim when touched. In order to determine the morphological features of this species, studies were performed at the Laboratory of Entomology of the Pontifícia Universidade Católica do Rio Grande do Sul. The morphological aspects of eggs, larvae, pupae and adults are discussed as well as illustrated with pictures and drawings. The eggs are light green, 1.98 mm mean height, 1.45 mm large and 1.61 mm long. From the first to the sixth larval instar, the insect has spines on the body with different sizes and they are green-brownish with strong and dark heads. The mean sizes are 5.19 mm long at the first larval instar and 53.49 mm at the sixth instar. The head capsules are 1.01 mm and 4.83 mm wide at the first and sixth instars respectively. The mean lengths of the pupae are 28.73 mm for males and 30.23 mm for females. Adults have sexual dimorphism in which the male is smaller and yellow and the female is larger and grey-brownish. The mean adult wing span is 60.47 mm in males and 80.33 mm in females.
Insecta; morphology; urticant caterpillar; stages
