Finding weird bugs near my lizard's enclosure...What Are They?

The last couple of months, I have been finding these termite-looking bugs in & around my bearded dragon's enclosure. Some are winged & some are not. I find several everyday dead in his water. Sometimes, one will just be crawling along the floor. I have found some black droppings (looks like pepper) on the wall behind his home. I don't get where they are coming from. I have moved things around & I can't find their nest. I don't even know if they have a nest. They don't seem to be bothering my dragon. Is it possible they are coming from my neighbor's unit above me? Any ideas would be helpful...Thanks