ventilation is key!
also, how warm are you keeping them? anywhere between 75-85F is the best.
how quickly are they dieing? i usually get about 100 adult crix at a time and a few die each day for whatever reasons; when i get 100 or so medium crickets, i only have a few die in a few days. it seems the bigger the habitat, the fewer die - at least that is what i've noticed in my experience.
TIPS:
*fresh food everyday - veggies & greens & dry gutload
*for the fresh food try to use only what they can eat in a day, it will become moldy or rotten and cause an outbreak of bacteria killing off a bunch of the crix
*water every day (sponge, moist paper towel, or special watering system)
*provide cross ventilation in the cage/container if possible
*full aluminum screen opening in the lid ~ if homemade
*place egg carton vertical so poop and dead crix don't collect in piles inside, instead it all falls to the bottom
*sweep out dead crix and poops a few times a week - everyday if there is a high mortality rate
*total darkness is ok but having a day/night cycle may benefit survival
well, i hope that at least some of that was useful. and if i forgot anything....
