Box Elder Bugs, like Asian Beetles, are over wintering beetles that are very active in the spring and Fall. Box Elder Bugs are aggressive around homes in the fall because they are feeding off of aphids from bushes and shrubs around the house.  They do get under siding and gaps in the home to find warmth. You will normally find them on the side of the house that the sun is shinning on the longest.  Exterior treatments in the fall is a essential service to control Box Elder Bugs and Asian Beetles.