Yes, Suspend Polyzone is labeled for use on flies.
We would also recommend a fly bait, such as Golden Malrin. It can be placed inside of a Fly Bait Station at least 4 feet above the ground so that it is inaccessible to pets. It can also be scattered around the porch and other places where the flies are.
No, vacuuming and mopping will not decrease the effectiveness of Suspend Polyzone. It should only be applied to your baseboards and cracks and crevices indoors.
Please let us know if you have any additional questions.