Human activity, commercial exchanges and climate changes current and future, could favor the (re)-emergence of vector-borne diseases, by inducing changes on Culicidae populations. This study aims to determine the potential importance of agricultural environments, especially cattle farms and equestrian, to welcome and favor the proliferation of some species of mosquito responsible for transmission of arboviruses. To better understand the structure of the Culicidae population and identify habitats favorable to the development of each species, a taxonomic inventory was conducted in 2008 (III, VI and X) and 2009 (V and IX) in ten cattle farms, and in 2011 (VI-X) and 2012 (VI-IX) in six equestrian farms located in Belgium. The harvest of mosquitoes is based on adult trapping by CO2-traps (Mosquito magnet) and on larval sampling at the level of 64 biotopes such as water troughs, used tires, abandoned utensils and temporary puddles or not. The morphotaxonomic of larvae and genitalia, and molecular study showed the presence of 15 species: Culiseta annulata Schrank, 1776; Cs. morsitans Theobald, 1901 Anopheles claviger s.s. Meigen, 1804; An. maculipennis s.s. Meigen, 1818; An. messeae Falleroni, 1926; An. plumbeus Stephens, 1828; Culex pipiens molestus Forskal, 1775; Cx. pipiens pipiens L., 1758; Cx. torrentium Martini, 1925; Cx. hortensis hortensis Ficalbi, 1889; Cx. territans Walker, 1856; Coquillettidia richiardii Ficalbi, 1889; Ochlerotatus geniculatus Olivier, 1791; Oc. cantans Meigen, 1818 and Aedes cinereus Meigen, 1818. Among the 57,680 individuals examined, Cx. pipiens s.l., Cx. torrentium and Cs. annulata are the dominants species and ubiquitous in all farms visited. The species of the genus Anopheles have strong ecological requirements and are therefore associated with some special habitats; other species however have a strong ability to adapt and therefore attend a wide variety of biotopes (Cx. pipiens s.l., Cx. torrentium and Cs. annulata). Water troughs, used tires and ponds are the most favorable habitats ...