If your neighbors are not practicing fly control - including use of an IGR - you're spinning your wheels, 'cause they'll just move over from the adjoining property.
Our kid is using the mineral with Clarifly IGR and garlic this year. IDK what it costs, but the garlic is a gimmick... the one study I'm aware of, out of Canada, showed something like a 47% decrease in hornflies in year one, but no effect in year two... but even in that first year, it never reduced fly numbers below the 'economic impact' level of 200 flies/cow.
Whereas Altosid(methoprene) IGR is effective against hornflies only, the newer Clarifly(diflubenzuron) claims efficacy against hornfly, face fly, and house flies.