Its important to keep the Calcium-Phosphorus Ratio in check and the calcium in the t-Rex diet is balanced for the diet not for the added feeder insects so you will need to dust them before feeding at least every second feeding of the bugs
I also use the REP-CAL CALCIUM W/ D3 and HERPTIVITE I m not sure if they still have the regular grade any more but I buy the ultra fine powder .. it sticks to whatever your feeding much better