What smell will keep rodents away?

Rodents including mice and rats have very sensitive noses and dislike certain strong, pungent smells that irritate them, but smell alone will not permanently keep rodents away if food and shelter remain available. The most commonly cited smells that deter rodents are peppermint oil with its strong menthol scent that overwhelms their olfactory senses, often applied to cotton balls placed near entry points, behind appliances, and in attics, though it evaporates quickly and needs frequent reapplication every few days. Other smells rodents dislike include cloves, cayenne pepper, eucalyptus oil, vinegar, ammonia which mimics predator urine, and the scent of predator urine itself like fox or cat urine available from garden stores. Some people use dryer sheets, but evidence is weak. While these smells may cause rodents to avoid a specific small area for a short time, hungry rodents will tolerate the smell if there is food nearby and they quickly habituate. Pest control professionals consider scent repellents as a minor supplemental measure, not a primary control method. The only reliable way to keep rodents away long term is to seal all holes larger than a quarter inch for mice and half inch for rats with steel wool and caulk or metal mesh, store all food in airtight glass or metal containers, fix leaks, remove clutter that provides nesting material, and use traps or professional exclusion services.