Which fly is characterized by a dull grey thorax, with a dull abdomen featuring yellow sides?

The house fly is characterized by its dull grey thorax and abdomen with yellow sides, making it easily recognizable. This appearance is typical of the common house fly (Musca domestica), which is often found in and around human habitation.

House flies play a notable role in the ecosystem but can also be problematic due to their association with unsanitary conditions and potential to spread diseases. Their dull coloration helps them blend in with various environments, increasing their survival rate by avoiding predators.

In contrast, fruit flies are generally smaller, with a more reddish-brown coloration and distinctive features such as large red eyes. Horse flies, which belong to a different family altogether, have a more robust build with larger eyes and typically exhibit a more pronounced color pattern, often with black and yellow markings. Gnats, on the other hand, tend to be smaller, with long bodies relative to their wings, and do not share the same thorax and abdomen characteristics as house flies. This unique combination of physical traits helps to correctly identify the house fly in this context.