To destroy flea colonies, use a multi-faceted approach: Treat your pets with vet-approved flea medications to kill fleas and prevent re-infestation. Vacuum regularly and dispose of the vacuum bag or clean the canister to remove fleas and eggs from carpets and upholstery. Use flea sprays or foggers in your home to target and kill fleas in their hiding spots, ensuring to follow the product instructions for safety and effectiveness.