Vine borers were our biggest nemesis in the garden in 2011. They completely destroyed all of our summer squash and a few of our cucumbers. The mother of the squash vine borer is the hawk moth. She lays her eggs near the base of a stem of a cucurbit (melon, squash, pumpkin, cucumber). When flying around, she flies and behaves a bit bee-like so no one realizes they are actually a moth. In retrospect I did see several of these flying around but didn't think much about them!
When the egg hatches, the caterpillar burrows into the stem and eats it from the inside.
The first evidence of vine borers is matter called frass that looks like sawdust protruding from along the stem. There are a few ways to do them in. You can poke needles through the stem until you find the offender and kill it (bleah). You can re-bury the stem at various points along the vine and it will grow roots. So even if the vine borer is digesting part of it, it can still get nutrients from the soil. Or you can use this nifty trick I learned—when the plant is young (6+ inches long) you can take toilet paper or paper towel roll and cover the base of the stem. It's apparently pretty effective at discouraging the vine borers from digging in. You can bet these will be all over our garden this year! I read elsewhere that nylons can work too. I'll be saving these as they expire both for this use and for holding heavy fruits on trellises as needed. I'm hoping (please, Hashem!) to get to complain about how I have zucchini coming out my ears. :)
Really enjoying this southern gardening thing, but I feel like I continually have whiplash.