Bio Spot Defense Spot On Dog Flea & Tick Control starts killing fleas and ticks within 15 minutes of application. Bio Spot Defense Spot On flea treatment kills fleas, ticks, flea eggs and flea larvae. The fast acting flea control treatment also kills and repels against mosquitoes. Bio Spot Defense flea drops are completely safe for use on dogs over 6 months of age. Bio Spot Defense Spot On Dog Flea & Tick Control prevents flea eggs from developing into adult fleas for up to 2 1/2 months. Additionally it also kills fleas and ticks for 3 weeks and kills and repels mosquitoes for 3 to 4 weeks. Active Ingredients: Etofenprox (CAS # 80844-07-1) 30.0%, (S)-methoprene (CAS # 65733-16-6) 3.6%, Piperonyl butoxide (CAS # 51-03-6)* 5.0%. Other Ingredients: 61.4%. *Equivalent to minimum 4.00% butylcarbityl (6-propylpiperonyl ether) and 1.00% related compounds.