Zucchini are Curcurbita pepo. Butternut is C moschata. So, no, they can't cross pollinate.

Agree, it won't work, unfortunately.

I like to grow Delicata Squash around my zucchinis since they are both Pepo and will cross pollinate.

This is very (pleasantly) weird...I left all the fruit on the bushes to wither and die, but checking today, I picked 8 fully-formed, 6" zukes that'll be part of my dinner for the next few nights. About the same number had yellowed and shrivelled. Still no male flowers to be found, and my nearest neighbour is a kilometre from me (and doesn't grow veges)...a mystery!

There are several zucchini varieties that are fully parthenocarpic. Sure Thing, Cavilli, Partenon, Perfect Pick ..... Many other s exhibit some parthenocarpic tendencies. These form seedless zukes without pollination.

Thanks for that info, farmerdill. These zukes are indeed seedless. Now if I could only grow seedless avocados and mangoes...