Which fly is identified by four longitude bands?

The house fly is identified by its distinctive appearance, particularly the pattern on its thorax, which typically features four longitudinal black stripes or bands. This characteristic is a key distinguishing feature that helps in identifying the house fly among other types of flies.

Each of the other fly options has different markings or physical characteristics that do not include the specific four longitudinal bands on the thorax that are synonymous with the house fly. For instance, fruit flies are usually smaller and do not have the same banded appearance, while horse flies are larger and have a more robust body structure. Flesh flies, too, have different patterns and are often recognized by their more metallic sheen and lack of longitudinal bands. Thus, the house fly's defining four longitudinal bands are a clear marker for identification, making it the correct answer in this context.