at a glance it looks like Tenodera sinensis Chinese mantis, the light green margin on the edge of its wings looks right. i think they may get that far north. very cool mantis and they do make great pets. my nephew has one we caught on our porch a few months ago.
Love these things. They're everywhere here in MD (US). I had one overwinter in my apartment a few years back. She basically lived "free range" in a couple of large houseplants I had pushed together so she could walk from one to the other. I'd catch her every day and put her in a metal bowl with a cricket so she could eat and drink. She made it almost all the way to spring, a fine accomplishment since she was already an adult when I found her huddled near my front door almost dead on a 30 degree night.
Although she didn't make it past February she did leave me something to remember her by; an unseen oothecae which hatched out while I was at work one day. They were everywhere...
Just found a few of these yesterday. they are a very neat species. Usually when I find females, they are already gravid. I once took one in for the winter like moltar and let her live free range as well. she laid her eggs under a leaf which I then incubated all winter and let them go outside the next spring. They defiantly are quite the characters.