Several weeks ago I bought three mantis egg cases at the local garden shop for about $6 (total), and two of them finally hatched the other day. As seen in the first photo, the egg cases are about the size of a walnut and contain up to 100 eggs each:




I didn't get quite 100 hatchlings, probably closer to sixty, and a number of them got stuck trying to escape the egg case.


I found a couple of photogenic ones that were good enough to cooperate with me and stay still for a few seconds:









They've been released in the garden, hopefully I'll be able to find them in a few months when they've grown to 3 to 5 inches so I can take a few more photos.