The essential oil from the leaves of Blumea mollis was extracted and the chemical constituents and the larvicidal against Culex quinquefasciatus effects studied. The analyses of gas chromatography (GC) and GC–mass spectroscopy (GC–MS) revealed that the leaf essential oil of B. mollis contained 39 compounds, and the major chemical compounds identified were linalool (19.43%), γ-elemene (12.19%), copaene (10.93%), estragole (10.81%), Allo-ocimene (10.03%), γ-terpinene (8.28%) and Allo-aromadendrene (7.44%). The essential oil had significant toxic effect against early fourth-instar larvae of C. quinquefasciatus with LC50 = 71.71 and LC90 = 143.41 ppm. The results could be useful in search of newer, safer and more effective natural larvicidal agent against C. quinquefasciatus.