Toxicity effects of tow insect growth regulators (IGRs) chlorfluazuron and flufenoxuron alone and their combinations with oils at quarter, half and recommended rates were studied by using  second (2^nd) and fourth 4^th larval instars of the cotton leafworm, Spodoptera littoralis. (Boisduval). The results achieved in this study can be summarized in the following, chlorfluazuron was more toxic on both 2^nd and 4^th larval instars than flufenoxuron when used alone at quarter, half and recommended rates. Concerning the effect of binary mixtures of the tested compounds at half-and quarter recommended dose, chlorfluazuron when mixed with Kz oil exhibited highly mortalities against 2 ^{nd i}nstar larvae of field strain of S. littoralis which caused 96.17% as residual effect compared with chlorfluazuron when used alone  (91.45%) at  half recommended dose.  While, chlorfluazuron + Hopa oil was recorded high mortality 94.47% at quarter- recommended dose as residual effect compared with chlorfluazuron when used alone (81.23%) at the quarter recommended rate .Also, Flufenuxuron + Hopa oil has the highest residual activity (95,25%) when compared to 79.10% for flufenuxuron alone at the half recommended rate. While, flufenuxuron + Misrona oil was recorded high mortality 82.93% as residual effect compared with 73.01%  for flufenuxuron when used alone at the quarter recommended rate . Also, regarding the chlorfluazuron when mixed with Kz oil exhibited highly mortalities against 4 ^th instar larvae of field strain of S. littoralis which caused  95.40% as residual effect compared with  chlorfluazuron when used alone  (92.94%) at the  half recommended rate.  While, chlorfluazuron + Kz oil was recorded high mortality 92.62% as residual effect as compared with chlorfluazuron when used alone (80.48%) at the quarter recommended rate .The data also confirmed that, flufenuxuron + Hopa oil has the highest residual activity (93, 5%) when compared of 71.53% for flufenuxuron alone at the quarter recommended rate . While, flufenuxuron + Misrona oil was recorded high mortality 79.29% as residual effect compared with 70.96%  for flufenuxuron when used alone at the quarter recommended rate . It could be concluded that,the oils when mixed with IGRS  enhanced the toxicity effect of IGRs against 2^nd and 4 ^th instar larvae of field strain of S littoralis.