I have been feeding my Ghosts houseflies and small crickets - but sometimes the crickets are too large or my housefly pupae are not ready/hatched so I opt for Hydei as my cultures are crazy full and the best I have. Also even if they have cricket or houseflies I tend to put in a few Hydei too as they still like them.
I tried small mealworms for them too. but have yet to have a mantis eat one.