I was camping out at lake Roosevelt (east of Phoenix) this weekend and saw a large Tarantula Hawk Wasp and was lucky enough to see it in action. They sting a Tarantula, drag it to a pre-made nest (Which was under this big bush) and lay a single egg on its body. The egg hatches and feeds on the tarantula while it is still alive. Pretty gruesome but hey...I didnt write the rules!
http://en.wikipedia.org/wiki/Tarantula_hawk
