An ootheca usually contains many eggs surrounded by a foam of protein which may then harden into a tough casing for protection. Notable ootheca-making insects are the mantis and cockroach.
I first thought this was a chrysalis, but internet searches helped me identify this egg sack. Nests are laid in the winter, and hatched in late Spring or Summer. We'll have to keep an eye on this one.
Facts and the picture are very interesting.often you see things and because you do not know what you are looking at you walk by. since i carry my camera with me most of the time i tend to take a picture of it just to go on the internet to read up on it.. we are never too old to learn more.
Even coming across this, I might never have suspected it would hold praying mantis! Everything you wrote and pictured here is new to me! 365 is a wealth of hidden information! Thanks for sharing!
http://365project.org/mags/365/2010-05-28