I'd consider not to come into contact with any chemical pesticides if I were you (they are extremely toxic and will cause all kinds of health and developmental issues, and many of them are biotoxic/carcinogenic).
if it's flies (houseflies), consider using sticky tape and also keep your house clean.
If it's mice, use rat/mouse bait (the newer one, not the old "warfarin" type) or spring traps...
I managed to keep my parent's house rat free by using spring traps and the newer non-warfarin baits.