The forestry sector occupies a prominent place among the economic segments in Brazil, with the cultivation of Eucalyptus sp. Among the numerous insects that can damage eucalyptus crops, the Saturniidae family has been noted as a secondary and main pest. The objective is to describe some bionomic aspects of Cerodirphia opis (Schaus, 1892) and to identify its natural enemies in the laboratory. Larvae were collected in stands of Eucalyptus sp. and raised in nylon mesh cages. Biological parameters were obtained under temperature conditions: 25 ± 1ºC, RH 80 ± 10% and 14-hour photophase, with daily observations. Only 11% of viability was observed in the larval stage. 32 males and 7 females were obtained, which represents a sex ratio of 0.18. The length of male pupae ranged from 20.57 mm to 26.46 mm, width ranged from 8.28 to 11.07 mm and weight from 0.31 to 1.930 g. The females were 10.42 to 12.85 mm, 8.28 to 11.07 mm and 1.91 to 1.93 g respectively. The parasitoid of larvae Megaselia scalaris (Loew) (Diptera: Phoridae) was found as a natural enemy, being the first recorded in Saturniidae.