When Spike was 14 inches, I started feeding him adult male dubia. I did, however, remove their wings so he was eating mostly soft meaty roach. You can use scissors to clip the wings or do what I did and quickly pull them off. I did feel sorry for them having their wings ripped off, but that was the least of their concerns as they got pretty mauled and chewed up by Spike. I console myself with the knowledge that they have such a rudamentary nervous system that they don't really feel pain in the way we define it. But still, clipping made me feel better.
Eric