My first guess would be squash vine bore. The yellow stuff is confusing.

Squash bugs? I'm looking at what look like clusters of yellow eggs in the picture. Some good discussion here.

http://forums2.gardenweb.com/forums/load/cornucop/msg061722117397.html

I don't think those are Squash bug eggs. They lay on the underside of the leaf and are small and coppery brown colored. I saw a lot of the squash bug eggs this summer (d@mn it all). I am way to familiar with them. They will lay them in the area defined by a leaf veien in weird V shaped phalanxes. That is just the area (in your picture) that a squash vine borer will enter the squash vine. It looks kinda like very fresh frass. I would not swear by it. Did it retain the yellow color. It could be lady bug eggs.