What I was told with the nightcrawlers (Canadian or European .. NOT red wrigglers ) is for babies to cut them to the size of space between their eyes. Worms are on my list to try to feed mine again but when I tried before he seemed to be afraid of it.. would back away when it wiggled n hit him in the face.. idk mine came from petsmart and was for the most part ignored and from what I was told only had a couple of crickets dumped in to the tiny critter keeper in the morning n pretty much just left there so probably never seen a worm in his short life..

As far as Dubia, there is a seller here , Ash of Ready Reptile Feeders, I think he is in Illinois and can ship them, its where I got mine from and they had to go to North Carolina..