Excerpt from Brian Sandle :

Recent news has stated how Monsanto are embarassed by this: many GM crop
fields are now plagued by weeds resistant to Roundup herbicide. That means
extra doses of Roundup and other herbicides are being applied. Does any
of it stay in the cotton lint, and on to the spun thread?

If the lint of Bt cotton does not contain Bt I wonder if insects will
adapt to eating mainly the lint, thereby escaping too much toxin. Does a
wood borer get energy from cellulose?

Heavy use of Roundup for weed control in connection with Roundup-ready GM crops
whose seeds are produced by Monsanto leads to the weeds evolving resistance to
Roundup, just as insects have evolved resistance to insecticides.

I don't know about wood borers specifically, but many herbivorous animals
digest and get energy from cellulose, which is a carbohydrate. Herbivorous
animals can thus live on a diet that would leave humans far short of energy and
protein. I presume wood borers would get energy from cellulose, since wood is
apparently a nutritious food for them.