An entomological study was conducted during the construction of a small hydro-agricultural dam at Raffierkro near Bouaké, in central Côte d’Ivoire, between June 2007 and November 2009. The objective of this research was to evaluate the variation in specific diversity, abundance and nuisance of mosquitoes species in correlation with the different stages of the dam implementation. Larvae were collected using a ‘dipping’ sampling method in irrigation canals, stagnant water footprints and fish breeding ponds to determine specific diversity. Adult mosquitoes were captured on human bait over 2 to 3 consecutive nights. A total of 20,925 adult mosquitoes and 489 larvae were collected, divided into 6 genera and 21 species, with the most prevalent being Anopheles gambiae and Mansonia africana. Abundances exhibited considerable variation from one year to the next, with a marked increase during the rice-growing season, which was accompanied by a significant nuisance, particularly in localities in proximity to the dam and rice-growing facilities. This study highlights the impact of the facilities on culicid dynamics, with potential implications for disease transmission.