Each bug has its benefit. I believe variety is the key in any diet.
My understanding is that butters do have a fat content as well as calcium.
Protein is found in hornworms (very high protein equal to protein in 36 crickets) and crickets (gutloaded) but one has to worry about feeding too much protein as kidney issue would result. Crickets would be like filler as well with additional benefits provided gutloaded, Unfortunately I don't see being able to get away from feeding crickets altogether.
Wax worms are nice treat, most reptiles love them but the fat content is high. They are good to feed when an animal has laid eggs or needs to put on weight. - Straight fat no real benefit other than putting weight on quickly.
Superworms are fat content as well but 'bad fat' compared to a wax worm 'good fat' if ever such a thing. This is where I had been told supers are like mcdonalds every day.
Of course the feed is only as good as the gutload.
I never understood why some bugs eg. meals are shipped in bran...so they are eating right...superworms around here come in dirt! What benefit is in potting soil for bugs to be eating & in turn feed to reptile?
Anyways to your original questions, here is a quote directly of a bug suppliers website: (
www.silkworms.ca)
"Butter Worms are high in calcium, they have a higher calcium content than any other feeder insect equal in size."
" Silkworms contain superior amounts of calcium, proteins, vitamins and nutrients"
I'd check out the info on some other main feeder suppliers and see what their facts state about the products as well. Another good one for Canada is
www.canadianfeeders.com.