Ant colonies feature a hierarchical social structure in which thousands of sterile female workers maintain the nest, forage for food, care for larvae, and protect one or more queens, whose sole responsibility is to ensure the continued survival of the colony by laying eggs. Most colonies form when the new reproductive queens leave their old nest, mate with a male, and deposit their eggs at the site of the new colony. New reproductive queens and males are characterized their wings, which worker ants lack. In a ritual known as a nuptial flight the winged ants, also known as alates, depart from existing colonies when prompted by the weather, fly to a new location, and mate. The alates mate in swarms either aerially or terrestrially. The newly mated queens then fly off to locate a nesting site, detach their wings, and lay eggs. Winged males, on the other hand, die after completing the nuptial flight as they exist solely to mate with the queen. The swarming presence of winged ants indoors, especially during winter, strongly indicates a nearby colony.