The answer to 'why is my ant swarms' is that ant swarms are typically caused by a nearby ant colony. When an ant colony becomes overcrowded or needs to establish a new nest, the colony will produce winged ants, known as alates, that swarm out to mate and start new colonies. Ant swarms are a natural part of the ant life cycle and are most common in the spring and summer months.
Ant swarms can be a nuisance, as the winged ants may fly into homes or gather in large numbers around lights at night. However, ant swarms themselves are not harmful and the ants will soon lose their wings and disperse. If the swarm is originating from a nest on your property, you may want to consider treating the nest to prevent future swarms. For severe or recurring ant problems, it's best to call a professional pest control technician.