You can buy praying mantis' get a bunch and put them around your yard, from what I have seen they stay around, as do the off spring.
I'm on a first name basis with my praying mantis.. mantises.. mantids.. whatever. Any mantis or tree frog I run into while I'm out and about typically ends up going home with me. Now if I can just have a chat with the bull snakes and convince them to just eat the mice and not the frogs I'll be set.