Are you sure you're looking at females? Females have a swollen stem behind the flower and it has a different shape depending on which kind of squash you're building. My crooknecks have a bulb while my zucchini have a thicker stem than the males but not a bulb shape. I had never grown squash before this year, and it's been a learning process. "Why are my males so big and the females so small/non existent? When will my female flowers bloom? How do I know if they're pollinated? When do I harvest them? What happens if they don't pollinate?" I found myself tackling all these questions in about two weeks as suddenly my plants started pushing out female flowers and fruit. To answer your question completely, I've never seen a female flower without a swollen stem behind it that eventually becomes fruit, and if there isn't any, then I don't know what could cause that. :(

I wouldn't try growing Butternut so far north. They require more warmth than the Peops or Maximas. I can grown them down here in Western Oregon and have a fine tasty crop. But I cannot fully ripen them with a hard shell needed for long term storage. Freezing only. I would think it would be worse for your climate, but maybe you get more warmth and less clouds, I don't know. I would recommend growing Delicatas. They're a Pepo and ripen in a quite timely manner up north. I have found that they do store quite well too, just not quite as long as a well-finished Maxima.

How do you tell the difference? Look at the stem of the flower. Male flowers will have a longer, skinny stem, but female flowers will have a tiny "fruit" at the base. These aren't actually a full fruit, and if not pollinated, they will drop off. In the case of summer squash, these are sometimes picked even before the flowers open and eaten petals and all. Alison Stewart (aka Torquill)

The females die if not pollinated so hand pollinate them. There is a FAQ here all about how to do it. One male can be used to pollinate several females. But do keep in mind that while a plant can 'look' healthy it can still be stressed and when stressed it will fail to open blooms (they only open briefly very early in the morning anyway) and abort the fruit/blooms. There are a couple of earlier discussions about this issue running right now so you may want to check them out too. Dave