Not sure why most of your leaves are brown and crunchy, but the issue is whether the stem connecting to each squash is dead. If that stem is brown and crunchy, you need to pull the squash. If that stem is still green, the squash can continue to mature on the vine. To the extent you want to leave squash on the vine to mature, why wouldn't you water the vine? A dead plant doesn't mature squash. If you haven't been watering, that certainly could explain the brown and crunchy leaves.

My patch now has a number of yellow leaves, but the squash are still coming on strong. I still have a couple of months of growing season, in principle. The yellow leaves might just be damage from the fierce heat we had. Sad to say, I just had a couple of female flowers with no male flowers to pollinate with. First time that's happened.

Looking at your zone, I wouldn't water -- the soil is cooling off now that it's mid-October, and if you haven't harvested yet you need to turn your attention to that. Keep an eye out for frost. A light frost won't really damage the fruits, but more than that and you're chancing decreasing the quality of the fruit; a heavy frost and they're ruined. Anything green isn't going to ripen in time (butternut aren't ripe as soon as they turn tan, they need more time on the vine after color turn). So yea...it's time to harvest up here in the north.

Thanks Dan and mxk! My next question is: Even if all the stems appear dead, is there any reason to let them finish ripening on the trellis, versus picking them and ripening on the porch or in the house? Thanks!

As I said, if the stems are dead, the fruit won't be getting anything from them. You can leave them on the vine, but they won't do anything on the vine that they won't do off the vine. So might as well remove them.

Are we talking green squash, or have they started to turn color? You say they "look ripe now." There is an active thread on this forum right now where they are trying to establish if green butternut can ripen (get tan and hard - fingernail test) off the vine. I think the issue is whether they rot before they do. While green, butternut squash are basically like summer squash.

Thanks Dan. I think they're all ripe. I think they might be happier outside, while the weather is still okay. I'll still let then sit awhile when I do bring them in, before I process them. Thanks for your help!

I think the way to look at it is that if the stems are dead, the squash are functionally already picked. That is, they are disconnected from any water and nutrient source. So you can store them outside on the dead vine, or store them inside not on a vine. As long as it doesn't freeze outside, I guess it doesn't really matter.

That's a good argument. Of course the way to extend the storage lifetime of a winter squash is to wash in disinfectant, like dilute bleach. Now, if you want to do that and then drop them back on the dirt because you don't have anywhere to put them, that won't help much.