What is a common characteristic of the house fly's adults?

The house fly is commonly recognized by its dull gray coloration and the distinct four dark stripes that run lengthwise along its thorax. This characteristic is vital for identification, as it helps distinguish the house fly from other similar species. The dull gray coloration is typical of many common flies, but the specific presence of stripes on the thorax is a unique and identifiable feature of adult house flies. This visual trait helps in recognizing them, especially in contexts where pest management practices may be necessary.

The other options portray characteristics that aren't aligned with the typical appearance of house flies. For instance, descriptions of brightly colored or spotted bodies do not match the commonly observed dull gray, striped appearance, which is critical for accurate identification in pest control and agricultural practices.