The answer to 'why is my flea swarms' is that you likely have a severe flea infestation in your home. Fleas thrive in warm, humid environments and can multiply quickly, leading to swarms of these pests. Common causes include pets bringing fleas indoors, undiscovered infestations in carpets or furniture, and lack of regular pest control treatments.
Symptoms of a flea swarm include seeing many fleas jumping on your pets, feeling them bite you, and spotting flea dirt (their feces) on your pets' fur or in your home. To solve the issue, you'll need to treat both your pets and your home environment to get the infestation under control.