Try to increase the humidity by adding 5-10 ml of water everyday into the hydrostone, the larvae could dry up easily while turning into pupa. Also, leave small shredded pieces of papers or leaves the worker ants sometimes use it to wrap up the cacoon for protection.They are doing kinda good. Well i was going to ask you if you use any substrate for them? I seem to be having a problem with the larvae. They grow, and eat nicely. But when it is finally time to pupate. They start to produce silk and wrap them selves up, but half way through they just drop dead! I'm trying to figure out what could cause this? After i read this post i was checking for mites, but i don't see any.