This link has about the best advice I could give on squash borers. A bit tedious but doable on a garden scale. Until this year, I've always grown squash as early as possible, and have never lost a plant to the borer. This year I planted seed the first of July, so they may be a problem. Check the underside of leaves for groups of eggs and crush them with your fingers. Dead eggs can't hatch.
en.wikipedia.org/wiki/Squash_vine_borer
