The most effective deer repellents are liquid egg-based products, according to Mother Earth News. Frequent application increases the efficacy of these repellents. Other common types of deer repellents include those that contain blood and predator urine.
Egg-based repellents have a strong odor similar to that of rotting meat, which deer associate with predatory animals. Many egg-based products also emit an odor similar to predator urine. One highly effective egg-based deer repellent is Bobbex, which contains a blend of rotten eggs, blood, ground fish, wintergreen oil and cayenne pepper. Immediately after application, egg-based deer repellents emit a strong smell. The odor diminishes as the product dries but remains detectable to deer because of their superior sense of smell.