On d20pfsrd 'Phookas' write up is the same as any other creatures. So no, they are not restricted to female only. A trait like that would crop up in the description. Archives of Nethys lists them as Pookas.
Some Leshys however might be. As they are seed bearing (fruit) that would makes them the developed female part of the plant. The write-ups in general describe them as spirits that inhabit a plant body.
Disclaimer- I'm not a botanist.
Following that many ants and bees are female. Breeding males tend to be specifically produced.
Disclaimer- I'm not an entomologist either.
