In our part of CA, Frontline is completely useless against fleas! Terrible, because now you have to get an expensive vet prescription if the dogs get fleas. It's always been iffy with ticks... ticks have to bite the dog to work, but that's not helpful when they rub all the ticks off on your leg first! Frontline does work very well against mites on chickens!!
Yeah I have to do the expensive vet prescription stuff with the mutt. She has some sensitive skin. I dare use the hartz or frontline on her she acts like it burns her....practically foaming at the mouth. Poor girl. Since the Flea Infestation of 2017, she's been on Vectra 3D - seems to do the job.