Eggs in contact with fipronil at different concentrations (0, 750, 1000 and 1500 μg l−1) for 10 ± 2 days reached their maturity and the percent of hatching was measured. Fipronil did not act as an ovicide (hatching rate: 90.6 ± 8.5%; ANOVA, P > 0.05). Nevertheless, at a 750 μg fipronil l−1 or more, just born juveniles were not able to move correctly and some of them died quickly after hatching.