Why did my mantis die

i have had a young brunners stick mantis for a few months now. i have fed it only fruitflies and have taken good care of the flies. the cage was room temp. a few days ago i noticed its abdomen on the bottom curved and dragging the abdomen on the ground with a new brown coloration on the abdomen, but behaved normally still other than that. now it is dead and i have no idea why. please help.

It sounds like a digestive problem, or an infection of sorts. It could possibly be a bad feeder, but that seems extremely unlikely. It could also be constipation, which actually happened to a mantis of mine. The possibility of mold is out there, as well as the possibility of a bacterial infection, which seems the most likely to me. You can rarely do anything about those. 

It's often hard to tell the cause of death of a mantid you've been taking good care of, and it sounds like it was receiving good care. I would say bacterial infection or maybe an internal wound had something to do with it, and both of those things are out of your control. I'm sorry for your loss. 

Im sorey for your loss.