The present study includes the effect of the ethanolic and aqueous extract of Piper nigrum against the third instar of Culex pipiens molestus (Diptera:Culicidae) in different concentrations: 1, 1.5 ppm of ethanolic extracts of Piper nigrum causing 100% mortality of larvae in the second day of treatment, while the concentrations 5% of aqueous extracts of Piper nigrum caused 100% mortality of larvae in the second day of treatment. The concentration 2.5% caused 100% mortality of larvae after four days of treatment. The current study also detected the effect of 0.1% concentration of Piper nigrum aqueous extract. The effect of this concentration has been studied on the growth of the ovaries and their follicles along a period 96 hours after emergence of adult life. The results of this study has clearly shown that the concentration 0.1% of Piper nigrum aqueous extract gave a highly significant inhibitory effect on the growth development of the ovaries and their follicles.
