Stored product insect pests are responsible for considerable quantitative and qualitative losses of agricultural products, mainly cereals and legumes. Solid-lipid nanoparticles (SLNs) by neem (Azadirachta indica) and castor oil (Ricinus communis) were synthesized using the ultrasonic solvent emulsification technique. The particle size and morphology of produced nanocapsules were characterized using transmission electron microscopy (ТЕM) and evaluated in the laboratory. This study aimed to evaluate the contact and residual toxicities of the two natural oils, castor and neem oil, loaded into solid lipid nanoparticles pre and post loaded-SLNs against the adults of three stored product pests, Sitophilus oryzae, Tribalium castaneum, and Oryzaeaephilus surinamensis, and their progeny production. Results indicated that the neem and castor oils pre and post loaded had insecticidal activities, but the prepared neem and castor (SLNs) formulation exhibited more toxicity against S. oryzae, T. castaneum, and O. surinamensis than that of bulk oil with low concentrations under laboratory conditions. Also, castor (SLNs) has the highest insecticidal activity with LC50 of 405.5 ppm, followed by neem (SLNs) (785 ppm) against S. oryzae. While in the case of O. surinamensis, insect neem (SLNs) had the highest insecticidal activity with LC50 (157.5 ppm), followed by castor (SLNs) (356.5 ppm). The results were also conducted to show that the direct and residual effects of neem and castor (SLNs), when mixed with wheat grains, were more stable and gave a high percentage of mortality at the concentration of 4.5% used even after one and two weeks. It also caused a significant reduction in emerged adults after six weeks and three months of treatment compared with bulk oil and control. These findings may highlight the role of solid-lipid nanoparticles the second generation of nanoparticles could be used successfully as an alternative to synthetic chemical insecticides in stored wheat as a protectant and can be used in integrated pest management programs for controlling the different stored products insect pests.