Prevention
for House Fly
Prevention denies flies both a place to breed and a way in. The core step is to keep the materials flies grow in from building up: manure, garbage, grass and weed piles, and other decaying organic matter. Source: https://extension.psu.edu/house-flies
Then keep out the ones that hatch anyway: seal cracks around windows and doors, fit good screens of 14- to 16-mesh, and use a swatter and sticky flypaper for the few that still get in. Source: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7457.html Source: https://extension.umn.edu/nuisance-insects/flies