Go for the first 2 suggestions as what you have is fungus gnats and they are after the cat food. Feed the cats only one time a day canned food and the only spray I know that will do away with fungus gnats is tat spray from family dollar stores or raid for flying insects. When my husband leaves the canned cat food out on the counter is when we get them and you can tell they are a little larger than an outdoor gnat. pesky things anyway.
as soon as they finish or a reasonable few minutes take up the excess food and clean the dish.
Pour some apple cidar vinegar with a couple of drops of dish washing liquid into a cup and leave them around where you see them. They will be attracted to the cidar, but drown. The DWL breaks the surface adhesion in the liquid, and they can't get out.
This is a sure cure, and safe for the pets.
To get gnats a non-toxic way. Spray the gnats with cheap hair spray! It must gum up their wings or something, but it does get rid of them without poisons!
I've had to fog my house twice since we got cats (indoor only cats). We just put our cats into their carriers and took them out with us. We rode around, picked up some food, and did some yard work. They stayed in the yard with us (in their carriers) after we opened the windows to air out the house. After we let them back into the house, we just kept an eye on them for several days to see if they had any reactions, but both were fine.
Make sure you protect their food and toys. It has been many years since we fogged, but I think I either double bagged those things, or set them out in the garage while the house was being fogged.
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