Hey, yes, these worms are fine. Another name for these bugs are pheonix worms. You will find that pheonix worms are very popular for bearded dragons to eat. Both young and old beardies can eat them. These are good live feeders because they are low in fat, easy to feed, and they are very high in calcium compared to most other feeders. Just be aware that you cannot collect them from the wild and feed them, as they could contain parasites or pesticides which have to potential to harm your bearded dragon.
Good luck!