I've seen those little guys, but they never have caused any problem for me, as annoying as they are.
What I have to deal with are the EVIL SQUASH VINE BORERS!! AAARRRGHHH!!!
Do a google image search, they are little moths that look like wasps, hard to spot, they only lay less than 5-10 eggs on a plant but those dirty little buggers get right down in that stem by the root and tear it up. The whole plant will die even though the leaves are almost intact. The leaves will start wilting and turn yellow and then die, over the course of about a week.
Hmm....check those stems!! You might be suprised to see some "maggot" type things in the stems.
You can limit them by putting stuff(poison, lime, diatomatious earth,etc) on the stems where they lay the eggs, carefully cutting the stems open and impaling the worm, and also piling dirt on the damaged stems.
That's my experience, anyway, for what it is worth.