A family that contains several species, the only Picture-Winged fly found in Colorado is Ceroxys latiusculus. Approximately the size of a housefly, these flies are typically found inside homes in early fall.
Much like the Cluster fly, Picture-Winged flies enter structures seeking a place to over-winter; however, a majority of Picture-Winged flies do not survive beyond November. This particular species have larva that develop in the seed heads of certain species of daisy and other composite flowers, although other species are known to develop on decaying matter which often results with them being confused with “fruit flies”. Unfortunately, little information is currently available about their biology. These flies are typically gray to brown in color with notably dark patterned markings on their wings.
As with Cluster flies, exclusion is the primary method of preventing infestations; sealing gaps cracks and crevices on the interior and exterior of the home prior to autumn aides in eliminating potential entry points in which the Picture-Winged fly can enter the home. Their invading numbers are typically significantly less than that of Cluster flies and combined with their decreased likelihood of over-wintering a full season, Picture-Winged flies are considered a minor nuisance. Prior to entering homes and structures, Picture-Winged flies may be found sunning themselves on sunny exposures of the exterior of the building.