BT (bacillus thuringensis) is usually pretty good on those borers, if you get them very early, just as the blossoms start to appear. Someone (was it here? I've been reading a couple of garden sites this week) said to try injecting it. This year is when I heard about the blossom timing, so will give it a try next year. I don't want to use even BT unless I have a target in mind, or it will kill beneficial stuff also. Trichagrama wasps didn't seem to make much difference this year. I probably needed to put them out more than once in the spring.
Mechanical removal is best for some of these pests. Too bad I don't have any ducks to feed the worms to. I have done the surgery Bobert describes, and gotten a few more before the plant finally shut down.