This fly could be most likely a flesh fly (Sarcophaga haemorrhoidalis), a member of the family Sarcrophagidae.
Adults are greyish with red eyes. There are usually three black stripes on thorax and a 'chessboard' pattern of grey and black on the abdomen.
The adults of S. haemorrhoidalis resemble house flies (Family Muscidae) in their general appearance, but are larger and more robust, ranging from 8 to 14 mm in length.
Sarcophagid flies can also be differentiated from muscid flies by the presence of three dark longitudinal stripes on the thorax instead of four.
Adult S. haemorrhoidalis possess black-colored bodies covered with a whitish powder-like substance that gives them a grayish tint.
Sarcophaga haemorrhoidalis is distributed throughout the world and is frequently associated with human and animal remains both in Canada and the United States (Byrd and Castner 2001). This species can be found year-round in the southern part of the United States (Byrd 1998-2011) and is absent only from subarctic areas (Madubunyi 1986).
To learn more about flesh flies, see this link: http://entnemdept.ufl.edu/creatures/misc/flies/red-tailed_flesh_fly.htm.
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