Objective:To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris(P.sylvestris)and Syzygium aromatkum(S.aromaticum)against Aedes aegypti(A.aegypti)and Culex quinquefasciatus(C.quinquefasciatus).Method:The chemical composition of the essential oils of both plants was determined using GCMS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A.aegypti and C.quinquefasciatus in accordance with the standard protocol.Results:The results as determined by GC-MS showed that oil of S.aromaticum has eugenol(80.5%)as its principal constituent while P.sylvestris has 3-Cyclohexene-1-methanol,.alpha.,.alpha.4-trimethyl(27.1%)as its dominant constituent.Both oils achieved over 85%larval mortality within24 h.The larvae of A.aegypti were more susceptible to the oils[LC_(50)(S.aromaticum)=92.56 mg/L,LC_(50)(P.sylvestris)=100.39 mg/L]than C.quinquefasciatus[LC_(50)(S.aromaticum)=124.42 mg/L;LC_(50)(P.sylvestris)=128.00 mg/L].S.aromaticum oil was more toxic to the mosquito larvae than oil of P.sylvatris but the difference in lethal concentrations was insignificant(P>0.05).Condusioii:The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control. Objective: To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris (P. sylvestris) and Syzygium aromatkum (S. rosamaticum) against Aedes aegypti (A. aegypti) and Culex quinquefasciatus (C. quinquefasciatus) : The chemical composition of the essential oils of both plants was determined using GCMS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A. aegypti and C. quinquefasciatus in accordance with the standard protocol. Results: The results as determined by GC-MS showed that the oil of S.aromaticum has eugenol (80.5%) as its principal constituent while P.sylvestris has 3-Cyclohexene- 1 -methanol, .alpha., alpha.4-trimethyl (27.1%) as its dominant constituent.Both oils achieved over 85% larval mortality within 24 h. The larvae of A. aegypti were more susceptible to the oils [LC 50 (S.aromaticum) = 92.56 mg / L, LC 50 (P .sylvestris) = 100.39 mg / L] than C. quinquefasciatus [LC_ (50) (S.aromaticum) = 1 24.42 mg / L; LC_ (50) P.sylvestris = 128.00 mg / L] .S.aromaticum oil was more toxic to the mosquito larvae than oil of P.sylvatris but the difference in lethal concentrations was insignificant (P> 0.05 ) Condusioii: The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control.