We bought a rental house last summer and all the window sills had tiny black bugs on them. Then we noticed them on the floor and in the closet. They appear to have a short life (individually), but as a whole - they last through the summer. We vacuumed them up only to have them reappear the next time we were there (a week later) and we kept repeating the process. They were finally gone by November. Now our renters are complaining of bugs with the same description. What are they and how can we get rid of them? Please HELP!