When you consider the high rate of reproduction and the distance that bedbugs can travel, an extreme infestation of a single apartment or condo can create a domino effect. As the bedbug population grows, the pressure for more food can send insects scurrying through the wall voids or down the hallway. Before long, the infestation in one apartment can move to another, spread to a whole floor, then move between floors. Most of the time, there are no solid barriers between apartments or condos, so a light switch or outlet cover provides direct access to the next unit and conditions they favor, both darkness and the close quarters. Once in the wall void, their search is aided by carbon dioxide exhaled by the occupants in an adjoining living area. The higher the occupancy, the more attractive the new space.