Activity directed isolation studies of the ethanol extract ofBontia daphnoidesL (Myoporaceae) leaves and stems led to the isolation of epingaione, a sesquiterpene furan. This compound was previously described by Chinnock et al. (1987) from the same plant. The compound showed growth regulatory activities on gravid adult femaleBoophilus microplusCanestrini (the southern cattle tick). The dose required for inhibiting the hatching ofB. micropluseggs by 50% (Fid50)was 0.4±0.06 mg/g of the tick body weight. The Fid50dose inhibited the sequestration of protein into eggs oviposited by 80%. These eggs were non-agglutinated and wrinkled. Histological examination of ovarian sections from the treated ticks revealed significant degeneration of funicle cells and reduction in yolk content.