Houseflies fortunately follow the simplest (possible?) system, as maturing females make their primary stimulant after 3 days. Fortunately mature males in large cages responded dramatically to one compound, either natural or synthetic (Z)-9-tricosene by massive mating attempts. And separated females were attracted to sugar cubes or sugar-treated paper with this natural or synthetic pheromone component. Trying to initiate the same behavior with alkanes was unsucessful, releasing frustratingly little behavior. Other Muscid spp followed the same behavior patterns in my tests lab and field in Florida looking primarily looking at alkenes, though none were as dramatic as houseflies. I was not allowed to work on blowflies. Your fly results sound rather like our other Muscids.