I was pruning a large Buddleia (Butterfly bush) this week at a job when I found a whole bunch of Praying Mantis egg sacks. At first glance it's difficult to tell if they are new(with babies inside) or used and empty. All are glued to branches and hard. Since I was trimming branches anyway, I brought them home. In this photo you can see closer. Can you tell? The whitish one is new with eggs. The two brown ones have tiny pin holes down the center edge. That's where the babies came out. I took the white one and taped it to a stake on one of my Purple Hopseed Bushes in my backyard. I'll be watching in March and April to see them hatch. Keep an eye out for these in your yard.