Larvae and pupae of Culex idottus have been collected in large swamp marsh depressions with grasses, sunlight, pH between 5.50 and 6.79, together with larvae of Aedeomyia squamipennis, Nyssorhynchus albitarsis, Anopheles annulipalpis, Culex brethesi, and species of Mansonia, Psorophora, and Uranotaenia.