they do not require a heating pad.. as long as you have a basking lamp pushing the temp to 105 and a
uv lamp.. keeping calcium on your crickets.. you should have a healthy beardie... what kind of substrate did you have? carpet? sand? millitt?
Sometimes they will die because of eating sand, which they cant pass... including cal sand...
If you go again.. look for walnut shell sand.. its basically powdered walnut shells... and make sure you are using reptisafe for the water, and cal dusting your crickets..
keep in mind.. desert temps (i know they are from Australia) but they can range from 40* at night.. all the way to 110 in the day... so i doubt anything like that contributed..