The apple maggot, Rhagoletis pomonella (Walsh) is reported from Utah County, Utah, where it has adapted to sour cherries. It has been taken repeatedly from pheromone traps in the vicinity of hawthorn (Crataegus douglassii), but there are no Utah data that suggest it has adapted to apples.
Jorgensen, Clive D.; Allred, Darin B.; and Westcott, Richard L.
"Apple maggot (Rhagoletis pomonella) adaptation for cherries in Utah,"
Great Basin Naturalist: Vol. 46
, Article 20.
Available at: http://scholarsarchive.byu.edu/gbn/vol46/iss1/20