RNA interference (RNAi) is a gene silencing mechanism that has shown great potential as novel, species-specifictool for insect pest management. This mechanism has been successful against several important insect pests; however, the efficiency of RNAi is inconsistent among different taxa and very challenging in Lepidoptera. Several biological barriers have been described for this important insect group, such as a high alkaline gut environment, the presence of RNases in hemolymph/lumen and endosomal entrapment. These barriers limit RNAi’s broad applications for pest control. In this study, we aerosolized poly (lactic-co-glycolic acid)(PLGA) nanoparticles (NP) coupled with targeted siRNA. TheNPs were coupled with siRNA to evaluate RNAi for the acetylcholinesterasegene (Ach) in the fall armyworm, Spodoptera frugiperdaand targetining the chitinase(Cht) gene in the European corn borer (Ostrinia nubilalis). Both species showed significant knockdown of gene expression, although results varied among separate experimental trials. The results of this study showed that PLGA nanoparticle emulsions delivered through the respiratory system can provide successful RNAi responses in Lepidoptera, but additional improvements are needed for robust and consistent responses.