Jeanne is right on here. Silkworms and Superwors are always best ..Mealies are worse that crickets when it comes to impaction risk as they have a very high Chiton Shell to meat ratio. and as far as the greens go...it really depends on the Beardie, sometimes it takes them a few years and sometimes they just naturally start loving greens off the bat at a young age. let them decide when its time for heavy greens. The superworms have very little chiton and its safe to feed them to beardies over 6 months or 15 inches and after a fresh molting you can feed them as young as 4 months at the earliest but it would be safer to stick with silk worms or wax worms. untill 6 months.