Hey, indubitably—as long as they're not too big for him to handle. I've seen some really small mealies (like in the tiny cups at the local pet chain) up to giants (also in the tiny cups at the local pet chain). ?
I feed my leos mealworms, but not exclusively. I also give them bsfl, a couple of wax worms, silkworms and the occasional small roach. I haven’t given them mealworm pupae as they don’t move much and seem quite crunchy. I would think darkling beetles may be too big.