Nano-encapsulation of essential plant oils may prove to be the most effective approach to overcome their application challenges against insect pests. Larvicidal properties of polyethylene oxide/polyacrylamide (PEO/PAAM) nanogels of mandarin essential oil (MEO) against Culexpipiens larvae were investigated. The nano-gel was prepared using an intramolecular crosslinking method initiated by gamma irradiation. The resulting mandarin essential oil (PEO/PAAm) nanogel (MEON) exhibited monodispersity, a relatively small size distribution, and a low negative surface charge of -1.1 mV, suggesting enhanced stability and reduced electrostatic interactions. The 2^nd instar larvae were more sensitive to MEON than the 3^rd and 4^th instar larvae at the lower doses of 10 and 15 ppm. The LC₅₀ and LC₉₉ for the MEON were (11.5 and 18.4 ppm) for 2^nd instar larvae; (14.5 and 23.6 ppm) for 3^rd instar larvae; and (15.3 and 33.8 ppm) for the 4^th instar larvae, respectively, at 48 hours after treatment. These results shed light on MEON's physical attributes, surface qualities, and biological assay and suggest that it might be a useful substance for Culex pipiens management.