A few days ago I noticed a few flies in my kitchen window, which is on the west side of our house. We killed those and went to bed. The next day we had approximately 10 flies in the same area, I noticed some would fly across to the opposite side of the house in the morning to the sun. I assumed to be by the heat. It's now been approximatly 5 days and the problem is consistently getting worse. House is clean, trash is taken out. We haven't smelled anything unusual or noticed any dead animals. Why are they coming in to my cool indoors when they want the warm/hot outdoors? What do I do to get rid of them?

Flies hate these scents

Lavender oil - lavender is considered to be particularly effective against flies[1]
Citronella oil (dilute with water first)unless using citronella candles [2]
Eucalyptus oil (dilute with water first)[3] Keep away from cats
Pennyroyal oil (dilute with water first)[4]
Peppermint oil (dilute with water first) likely more effective against mosquitoes but also considered to work against horse-flies[5])
Lemongrass oil (dilute with water first)[6]
Cloves [7]
How to Make Natural Outdoor Fly Repellent with Essential Oils - wikiHow

Houseflies are attracted to light, rather than heat. Since they are already in the house, the best remedy is the old flypaper strip. You can still get them at hardware stores. While you catch the ones inside, look around the outside for wet, decaying organic material. It doesn't have to be animal, mulch or leaves can be breeding sites. Turning the plant matter to dry it some will help get rid of the flies and still feed bushes/trees/flowerbeds.

I am having the same problem tomorrow I plan to go buy citronella candles and burn them all around the house I will get backto you and let you know if it works... It is driving me nuts they are just sitting on the wall like they belong there uughhh