In my experience that depends entirely on the dog, and what's on the lawn. If you left a juicy T-bone steak in the middle of your grass there's no amount of cayenne that'll keep 'em off. That said,...
There are several methods, from Flea Collars to special shampoos.
Generally, if you keep good care of it and wash it regularly, it won't get fleas/tics in the first place. Every now and then just...