Lookalikes
for House Fly
The stable fly matters most: it looks similar but carries a stiff, bayonet-like mouthpart for piercing skin and feeding on blood, so a biting "house fly" is almost always a stable fly. Size sorts out the rest at the extremes: the lesser house fly runs smaller, the cluster fly larger. Source: https://texasinsects.tamu.edu/house-fly/ Source: https://extension.umn.edu/nuisance-insects/flies