if you can get some kind of hypodermic needle, you can squirt BT inside the stem.

butternut is resistant to SVB ( v= vine ) as are all moschata. pumpkin and zucchini are pepo.

you can do a search of SVB and get lots of info.

Bt will not work for stem borers. After the eggs hatch, the tiny larvae immediately enter the stem where they begin feeding. Caterpillars must ingest the Bt for it to work, and at present, there is no way to deliver Bt to the inside of stems.

There are numerous IPM strategies that will assist you in controlling/preventing an outbreak of the pest in your garden.

Here is a link that might be useful: Squash Borer Fact Sheet

"Bt will not work for stem borers.". Yes, I knew that. What I was hoping was that next year, as soon as I planted the young plant, I kept BT on it, possibly the stem borer eggs would never be laid.
I will check the fact sheet, thank you.

Informative fact sheet.