Macrophyte-based wastewater treatment systems are recognized as an alternative for sewage purification in developing countries. Unfortunately, they also represent a favorable breeding ground for mosquitoes, thus a serious drawback that should be addressed despite the good promise of this technology.A 1-year study of mosquito production in seven ponds of a Pistia stratiotes-based domestic wastewater treatment plant in Cameroon revealed that approximately 43imagoes/m 2 per day rose up, among which 54% were female. Mansonia and Culex were the main breeding genera with about 55 and 42% of the total imagoes respectively. Culex bred mostly in the first three ponds (B1-3), characterized by a high organic pollution. Mansonia occurred in great number in the later ponds (B4-7), where the water quality was rather better and the roots of P. stratiotes well developed, thus permitting the fixation of a great number of larvae to the macrophyte roots. Though representing a favorable breeding ground for mosquitoes, only 0.02% of captured imagoes were Anopheles gambiae, suggesting that this wastewater treatment plant does not significantly contribute to the development of the malaria vector in this area.