In SoCal, over last 4 summers I have had to battle caterpillars which cased bud rot. First season, before I learned about Monterey BT, I lost about 8 oz out of a final yield of about 45oz off of three plants (18%). The next year, I used MBT, but a little too late, and lost about 5 oz out of about 50 oz (10%). Last summer, I learned, and sprayed early and often. Had an amazing yield of 100+oz on 4 plants (2 in 10 g and 2 in 15g pots) and lost maybe about 2oz total (2%). This summer went smaller and harvested about 40oz, but lost only about 2 oz (5%). In each harvest, did a thorough washing of the buds.
Sucks how those bastards always affect your biggest, best colas. A key is looking closely daily for even a tiny brown spot on the bud, and digging in to check. I discovered and killed at least 5 or 6 small caterpillars this season early enough to just cut part of the bud off, but saved the majority of cola from much worse bud rot. Key is daily diligence, for sure.