Will fleas die on there own?

our cat had fleas and he went off to the vets and got re homed due to his edgy ways and the kids almost a week a go , but we are still seeing fleas after sprays now that there are no animals in the house how long will we have them for? i hoover regularly and mop with bleach almost daily i read about them lying dormant but we have a sometimes really hot active house so i don't think they would also i read that they cannot lay eggs without having an animal to bite on is this true?