I used to hear a lot of funny tales about feeding mealworms to geckos. People used to say that they actually ate through the stomach and ended up killing the geckos. Although the Beardies aren't geckos I don't believe the mealworms are your problem. Howeveer, I believe that adding calcium dusted crickets as a main staple along with good veggies and mealworms or super worms given as a treat would benefit your Beardies. The Mighty Oscar definitely has a point with using a proven UVB "tube" light such as Zoo Med or Reptisun, etc. as they are PROVEN light sources. Metabolic Bone Disease is caused by a calcium deficiency in reptiles that cripples the poor little guys. I've been fortunate enough as a previous gecko breeder to have a Vet well versed in reptiles.