The insects in your submitted images appear to be psocids, not flies. Psocids are often found on trees outdoors, where they feed on mold, mildew, and decaying plant matter. They can sometimes build up in numbers, but they do not cause any damage to plants, landscaping, houses, etc. Outdoor species are not known to invade homes. If large numbers are found around doors or windows, an insecticidal spray for residential pests can be applied following the label instructions.

-Insect ID Lab, Virginia Tech