The answer to 'what causes stink bug' is that stink bugs are attracted to homes and buildings for shelter, food, and breeding. Stink bugs are a type of shield bug that release a foul-smelling odor as a defense mechanism. They are drawn to homes in the fall as they search for warm, protected places to overwinter. Stink bugs feed on a variety of plants, fruits, and vegetables, so they may be attracted to gardens, orchards, and crops near your home.
Stink bugs can also enter homes through cracks and crevices around windows, doors, utility pipes, and other openings. Once inside, they will congregate in large numbers, often gathering on walls and ceilings. Their presence and odor can be a nuisance for homeowners.