I don’t leave food out. Garbage gets tossed, counters are cleaned. I replaced half the windows in my home and caulked up the rest. I bought a salt gun and have been picking them off but there’s always more.
How do I figure out where these little fuckers are getting in?
For me it is in the hottest months and its in the recycling. The recycling bins are not as contained as the general bins, residual food is in the recycling from improper washing. Lone fly in through an open door and lays eggs in recycling, in normal times process from egg hatching to maggots to flies takes longer than the recycling collection period so it is all thrown out. Under very hot conditions it is accelerated and you wake up to 10 newly hatched flies on the inside of your garden door every morning. Solution is when it’s very hot put the recycling out more often even if it attracts foxes. This is very specific to me but something similar may be happening for you, I don’t think flies squeeze through small gaps.
Hmmmm I’ll try giving the bins a wash. I’m very particular about recycling being clean but I hadn’t considered they were coming in through the garage either…
However meticulous you are about washing recycling still enough organic material might be left for a fly to consider it a viable site to lay eggs. Also washing can sometimes work against you because putting things in the recycling wet can allow a licour to form over time that will smell as bad as anything you have smelled. Wash and disinfect the bins and in the hottest months put them outside. Do you note there is a limited age distribution in the fly populations you see, they are all young adults and all clean and shiny as if they have never been outside.
This guy flies.