It's been my experience they help with ticks. But I have had no indication they help with fleas. The dang fleas are tough, especially this Summer. At least they are for me.
Last couple of years we been worming with Cydectin cattle wormer, either down the mouth or down the back (5cc)and we have not had a flea or tick problem . It's for internal and external parasites on cattle.it has done a good job for us on worms.