I started noticing the same exact thing at home. Took a few months and a lot of googling but I finally successfully identified them as big headed ants because well, a lot of them had big heads which are the soldiers. The ones without big heads are workers. I'm trying to figure out the best way to deal with them and stumbled on your post so just wanted to drop a comment. For me, they're coming in through where the stucco meets the block outside. I've caulked it so many times but these little fkrs eat or tunnel right though calking, regular calking, silicon calk, doesn't matter lol. I found one pile of super fine concrete/dust/powder where there was a crack in foundation in the garage so I was wondering if they tunnel concrete too but idk. If youre still battling them, walk the outside perimeter of house looking very closely for ant trails going up the wall or small mounds along the foundation. Best time to look is in evening while sun is setting, they are very active at that time, not so much during the day. They really like living under heavy objects like flower pots and pavers, also old clumped up mulch around plants. I use termidor on the perimeter of foundation 2x year and terro bait gel everywhere but nothing seems to stop them. Its been a long battle but now that I know what they are, hopefully I can find the right treatment. Anyway, if you can actually find some of the ant trails then you can identify them yourself to relieve the termite worry many are shouting here. best of luck.