They're superworms. The larvae stage of the darkling beetle.
For the most part, their ratios are on average with a Ca:P ratio of 1:18. Protein content is slightly lower than a cricket, but higher than a pheonix worm and their fat content is around 18 which is a little high compared to the other feeder options.
To better aid in the health of your dragon, no one feeder should be used exclusively, but instead a combination. This elimates the actual "staple" clause.

. Naturally with the superworm, considering the fat content, you would feed signifigantly less compared to crix or roaches on average.