You may have pickle worms depending on where you are... I have never encountered inch worms on my squash or pumpkins in over 18 years of growing them. Pickle worms are a tropical worm that migrates up from the Gulf States each year starting in Spring, following the warming temps. They are a translucent green with tiny brown checker marks on their bodies and a dark head (unlike squash vine borers who are solid colored. Pickle worms will attack any part of the vine - stems, fruit, flowers... particularly the growing ends of the vines. Squash vine borers only attack the larger vine stems and the base of the plant. Pickle worms have only reached my garden in Virginia in our hottest Summers. they don't overwinter here. I would recommend trying some Neem oil spray, or Bonide's "Eight" spray. They are organic pesticides. Of course, if you are in an area that is starting to have cooler nights... squash and pumpkin vines don't like really cool nights. The leaves start to die off this time of year as the vines begin to collapse in order to expose the mature fruit to more sunshine so that the skin can color up and harden.

Hope this helps. Let me know if you still can't figure out what's happening.

Bobby