ABSTRACT
Flies in the families Muscidae (house flies), Calliphoridae (blow flies), and Sarcophagidae (flesh flies) are often termed filth flies because of their unsanitary breeding and feeding habits. For example, house flies, Musca domestica, regurgitate liquid through their proboscis as they probe around on various surfaces, and also may deposit fecal matter as they crawl over food sources. House flies occur worldwide in association with human dwellings and are about 5 to 8 mm long with a dull gray thorax and abdomen (not shiny) (Figure 19.1). The thorax has four longitudinal dark stripes, and there are pale yellow areas on each side of the abdomen. Mature housefly larvae are 10 to 13 mm long and usually creamy white
in color (Figure 19.2). Overall, the larvae have a conical shape very much like a carrot with two dark-colored mouth hooks at the narrow end and two oval spiracular plates or openings at the broad posterior end. There are no soft protuberances surrounding the spiracular openings in larval house flies. In addition, the three slits in their posterior spiracular plates of larvae are curvy as opposed to straight, which is a diagnostic feature for this species.
