Rebecca and spider pharm are great places to get houseflies from in a pinch
if you need a lot of hydei in a pinch, loose flies from fruitfly shop or hydei cultures from rainbow mealworms are my go-tos!
ghosts are odd little buggers. they eat and eat and eat but grow so slowly. talk about an inefficient metabolism!
ok there's nuance there
remember that all organisms use enzymes, which have certain thermal optimae. i bet room temp isn't the best for rearing ghosts; perhaps they'd grow much more rapidly at 85F? not sure