We are in the process of doing a few renovations to our house. One of the renovations was to tear out and replace the subfloor by the backdoor and the doorframe itself to rotting wood. We did this awhile ago and have not finished putting the flooring down there. I was feeding the dog (this is where his food bowl is and the bugs did not seem interested in the food in the bowls or the pieces on the floor) that’s when I noticed like 50 of these very very tiny bugs crawling on just the subfloor area and nowhere else. They were smaller than a grain of rice and moved pretty fast. There is a red spot you will see on the floor where something was spilled awhile ago but was cleaned up and just stained the flooring.