What smell do squirrels hate the most?

Squirrels have a very sensitive sense of smell and dislike certain strong, pungent odors that irritate their noses, but no smell alone will permanently keep them away if food and shelter remain. The smells squirrels hate the most include strong mint scents like peppermint oil and spearmint oil, which have intense menthol that overwhelms their olfactory senses, often applied to cotton balls placed near entry points, attics, and bird feeders, though it evaporates quickly and needs frequent reapplication. They also dislike the smell of hot pepper and capsaicin, which is why many squirrel-proof bird seeds contain hot pepper flakes, as well as vinegar, ammonia, garlic, and onion in strong concentrations. Other deterrent smells include predator urine like fox and coyote urine available from garden stores, and strong essential oils like eucalyptus, cinnamon, and clove. Some people use mothballs, but mothballs are toxic to humans, pets, and wildlife and are not recommended. While these smells may cause temporary avoidance of a small area, squirrels quickly habituate if highly motivated by food, and they will tolerate the smell to reach bird seed or a warm attic. Pest control experts consider scent repellents as minor supplemental measures, with the most effective control being physical exclusion with metal flashing and hardware cloth, squirrel-proof feeders with baffles, and trimming branches away from roofs.