Talks about plugging the holes in cocoa plants/trees (?) thus suffocating the borer. This is a cocoa farm in Ghana, Africa. While not a scientific study, it's a possible for sure. Cannabis on the other hand does not have a solid pith (center of stem) it's somewhat spongy so you'd think their was enough air inside for the little bastards to live (do worms breath?). Also the holes 'my' guys are making to bore inside are so tiny and seem to be plugged up with their brown grainy looking (and feeling) crap. Maybe the cocoa borer are eating the wood as they go and by plugging the hole you are cutting them off of their air supply?
I was going to say the same thing. Since the cocoa tree has such a dense thick exterior once the hole was plugged it would be easy for them to suffocate. Like you said, the cannabis plant is hollow and I don't think plugging the holes would do much, if at all. Also as you noted their own holes are often clogged so I don't think it would be very effective on cannabis plants. Definitely an interesting article though.
All insects breathe, though not in any shape or form that is remotely similar to humans. They have tiny holes along their abdomen called spiracles that they use to take in oxygen as they need it. They can adjust the openings and even close them off to retain moisture. I think their already minimal oxygen requirements combined with the excess O2 that is bound to be floating around inside the stem where they reside would render plugging efforts futile.
Also due to the hollow interior of the Cannabis plant, it makes travel throughout the entire plant very easy for these caterpillars. Woodsman seems to have better luck at locating their entry points than I have had at my friend's farm, as I'm usually brought in late in harvest when they attack the buds as they usually don't cause my friend hardly any headache until the buds form.
I have some pictures I took a couple weekends ago when I was up helping him with a variety of things. Still working on that pest post, been extremely busy with school.
Here is a picture from my department, this is just one of dozens upon dozens of rows of insect collections. We even have specimens collected by Carl Linnaeus himself in our collection. Still a lot of work ahead of me....