piper gaudichaudianum grows abundantly throughout the brazilian atlantic forest. essential oil extracted from this species has been reported to have larvicidal properties. the aim of the study was to characterize the essential oil (eo) of p. gaudichaudianum and its insecticide activity on the third instar larvae (l3) of lucilia cuprina under laboratory conditions. groups of 20 l3 were placed on filter paper impregnated with increasing concentrations of 2.5-30% (v/v), equivalent to 0.39-4.77 l/cm2, solubilized in ethanol or acetone. the toxicity was determined by l3 mortality after 6, 24 and 48 h after contact. p. gaudichaudianum eo was also characterized using cg/ms. lethal concentrations of 50% (lc50) 24 and 48 h after eo exposure were found to be 3.69 and 2.19 when solubilized in ethanol and 9.14 and 6.05 l/cm2 when solubilized in acetone, respectively. the major compounds were germacrene b, -cadinene, -elemene, (z)-cariophyllene, -copaene, (e)-cariophyllene, -calacorene, -humulene and (e)-nerolidol. the study demonstrated the significant biological activities of p. gaudichaudianum eo (pgeo) compounds against l. cuprina.