I've raised all my mantises from L4 on mealworms. I just used a big tub with dried oatmeal and some cut up potatos. The only problem I've found with mealworms are that they dig into the ground, where the mantis can't get them. So in each of my mantises' cage there is a little (3 inches wide) ceramic dish at the bottom of the cage. The mantises sees it from the top, them climb down the wall, catch the mealworm from the plate, then climb back up. Mealworms are also easy to feed to a disabled mantis because you can cut them in half and stick them on a toothpick.