I Have A Puppy That Has Been Biting At His Tail Area And Back Legs. He Has Been Sprayed With Frontline. Is This A Sign Of Worms?

When a puppy has intestinal parasites often you will see diarrhea or sometimes you will see the worms in the stool.  Puppies with worms may lick or bite their anus and may scoot. 
All puppies should get 2 dewormings along with their puppy vaccines.  Bring a stool sample to your veterinarian to see if your puppy has worms and what type of worms.
Skin conditions can cause excessive licking or grooming.  Fleas (which the front line should take care of), mites, or ringworm are also possible.
Have a veterinarian do an exam to make sure there is not a skin condition or parasite causing this behavior.

It sounds like worms just get him out at the vets or get some worming tablets and see if it continues if it dose it has got to be some thing else. Hope this helps