Plants and their derivatives, such as essential oils (EOs), have been mainly used in recent decades as promising insecticides instead of the conventional insecticides. Lavender essential oil and its nanoemulsion were tested as larvicides against the Culex pipiens larvae to assess their toxicological and biological effects on the tested population. The bioassay test showed that both lavender essential oil and its nanoemulsion were effective against Cx. pipiens larvae,with median lethal doses (LC_50,s) 133.85 and 480.78ppm after 24 hours of treatment for lavender essential oil and its nanoemulsion, respectively. GC-mass spectroscopy results indicated that the lavender essential oil is mainly composed of 1-Propanol, 2-(2-hydroxypropoxy) (25.13%), 2-Propanol, 1,1'-oxybis (21.7%), 1-Propanol, 2,2'-oxybis (11.93%), Linalool (10.81%), Linalyl acetate (10.35%), 2-Butanol, 3,3'-oxybis (5.12%), and Eucalyptol (4.8%). While, the lavender essential oil nanoemulsion is mainly composed of Linalool (38.32%), 2-Propanol, 1,1'-oxybis (15%), 1-Propanol, 2-(2-hydroxypropoxy) (11.24%), (+)-2-Bornanone (9.78%), 1-Propanol, 2,2'-oxybis (9.46%), and Linalyl acetate (8.29%). Biology tests confirmed that both lavender essential oil and its nanoemulsion caused larval, pupal, and pupal-adult intermediate malformations.