Question: do hartz flea and tick collars work?
Answer: Flea collars can protect your pet for up to seven months, because they're designed to slowly release the bug-killing chemicals over time. ... If you have a puppy younger than 6 months, you can get him the Hartz® UltraGuard Plus® Flea & Tick Collar for Puppies, which will kill fleas and their eggs for months.