I sowed directly into the garden and the seedlings are up and just making their first true leaves. Should I start spraying now? Any reason not to? Any other suggestions?

The moths have to be prevented from access to the plants to lay their eggs - row covers are recommended for that. Once the eggs are laid you have to physically remove them as once the larvae hatches and immediately bores into the stem no spray will even come into contact with it.

Dave

Firstly, I'm painting the leading vines with Sevin. That way, the Sevin doesn't get everywhere. Not on the leaves, flowers, or fruit. Just on the vines that the SVBs are trying to penetrate. Just the leading vines. Not the leaf stems. I don't care if they kill a leaf. Takes about fifteen minutes every two weeks to do this, though when the vines are tangled, it gets a bit confusing. A cheap one-inch paint brush works great. I suppose a sprayer with a narrow spray head would work as well.

Secondly, I'm mounding dead leaves and mulch on the vines. The leaves stick up out of the mulch. If you bury the vines, the SVBs can't find them. If the vines root, so much the better. Of course, at the end of the season, you just dig the mulch in. Now, this is for vining squash. Might not work as well with upright squash.

So far so good. No SVB damage seen.