The above posts are all correct ... however .... there is a way to gut load a silkworm.
Heika is the one who initially experimented with this and I have experimented with it since hearing about it from her.
You can mix dry gut load, chopped or processed vegetables, etc. into cooked chow before it sets and the silkworms will eat this.
You cannot maintain silkworms on this diet. It should be fed to worms that are going to be fed off the night before feeding.
I repeat:
The worms that eat this will not survive longer than a couple of days so only offer it to ones that will be eaten soon.
Keep this mix separate and label it as gut load so you don't accidentally feed it to your silkworm colony.
-Brad