hmmm...mine have lasted for months with minimal die-off. How large is the container? To give you an idea I have about 25 left and they are in a 2.5 gal. glass tank with a piece of screen on top (that's just to keep my cat out! - she loves to dig around, pull them out and then play with them on the floor! I have no idea how many she has actually gotten and have wandered away!)
Anyway...my suggestions would be keep them uncovered, make sure they are not crowded (250 would need a large tub) and give them much deeper bedding. My 50 are in 3-4". Also be sure the bedding does not get wet or moldy. Frankly, I just use oatmeal for bedding and feed them carrots, apple, potato, etc. though the apple and potato will turn and mold quickly.
hope this helps!
lele
>>when i first received my shipment i had 250 juvenile superworms, i placed them in a tupperware container with about 2 inches of superworm bedding from cricketfood.com and have been giving them slices of carrots every other day or so for moisture
>>
>>the problem is im having a large percentage of fatalities, there are a lot of black ones on the surface not moving at all
>>
>>i thought these guys were supposed to be pretty resilient so whats the deal? any ideas?
-----
0.1 veiled - Luna
0.2 house geckos - Gaia & Tia (MIA 
0.2 felines - Kyndra and Líta