Bio Spot Defense Flea & Tick Spot On for Dogs 81 lbs & Over, 6 Month is a monthly topical flea control product that also kills ticks and mosquitoes. Dogs 6 months and older can benefit from the protection offered by Bio Spot Defense. The ingredients in this product keep flea eggs from hatching and larvae from maturing, thus breaking the flea's life cycle to prevent re-infestations.