One of my favourites for its so peculiar but endearing appearance. Can't you see where the old movies about space aliens got their ideas? These large (50-60mm) insects appear in late summer through autumn. They are highly predatory and will eat just about anything that comes close, including the much smaller male of the species! Young mantid nymphs will also eat each other, and this, so I have read somewhere, is why we never see these insects in any great abundance. Gardeners may know them as beneficial insects, eating all those insects that eat our plants (as well as eating other beneficial insects, unfortunately). The name comes from this pose which looks like they are holding their front legs in prayer. However, "preying" mantis would be an apt term too, as Stephen Marshall suggested.