He shouldn't be eating those at all... They have too hard of a shel and are hard for beardies, especially young beardies to digest. You should be feeding him crickets that are just big enough to fit between his eyes.
Pet stores usually have no clue how to take care of their reptiles, and often give out very poor information when they are asked.
I was in a petsmart the other day and they had ball pythons in a desert setup, and no heat source ( the temperature was 71 degrees and the humidity level was at 10%) I found the manager and told him that his reptiles were going to die if he didn't fix the problems. Luckily he saw reason , but it wasn't until I pulled up 3 care sheets on my iPhone