A dark unspotted phenotype of Anopheles (Cellia) maculatus Theobald, is described for adult males and females found in a colony of wild type (spotted) maculatus (Kuala Lumpur strain). Morphological differences are tabulated for separating the melanistic phenotype from the wild phenotype. The prevalence of the unspotted phenotype throughout 5 colony generations and data from preliminary crossing experiments between the dark and wild phenotypes are tabulated. Attempts to colonize the melanistic mutant were not successful.