What do fleas absolutely hate?

Fleas absolutely hate several things that can be used to repel and kill them, though no single repellent eliminates infestation alone without thorough cleaning and treatment of pets and home. Fleas hate strong, pungent scents from essential oils and herbs including cedarwood oil, lavender oil, peppermint oil, eucalyptus oil, tea tree oil, lemongrass, and rosemary, which have repellent properties and interfere with their ability to find hosts, though essential oils should be used carefully around pets especially cats as some are toxic to them in concentrated form. They hate citrus smells like lemon and orange peel. They hate desiccant dusts like food grade diatomaceous earth and CimeXa that dehydrate them by damaging exoskeleton, though diatomaceous earth must be food grade and used lightly to avoid inhalation. Fleas hate high heat, as washing pet bedding, blankets, and clothing in hot water and drying on high heat for 30 minutes kills all life stages including eggs, and steam cleaning carpets and furniture above 200 degrees kills on contact. They hate thorough vacuuming that removes eggs, larvae, and pupae from carpets, cracks, and pet bedding, with immediate disposal of vacuum bag outside. They hate clean, dry environments because flea larvae need humidity and organic debris to develop, so reducing clutter and keeping home dry helps. For pets, veterinary flea preventatives are most effective.