Why did my hen Die???

[shem]

I went to my coop this morning to find one of your easter eggers dead. Just laying on her back with no signs of trauma. I can't imagine what might have caused this. In the nesting box was an egg from the day prior, she was seemingly healthy. We do have a wasp problem this time of year. If she got stung may that have killed her? My concern now is protecting the remaining 24 hens. Any ideas of what to look for? Any other experiences with this happening?

Thanks!