There are many species of mantises worldwide. One species in Sri Lanka may reach 10 inches in length, and like other large species from South America, these large mantises may prey on insects, small birds and reptiles. Wherever they live and whatever their size, they share one gruesome feature: Every mantis is a perfect killing machine, a living steel trap. Anything but prayerful, mantises prey on everything that moves and can be overwhelmed. World-wide, there exist some 2,200 species of this bizarre insect family, most of them in the subtropical and tropical zones, a few in the temperate zones of the Old an the New World.