Waterscorpions in the genus Ranatra, Nepidae, Hemiptera
Waterscorpions (sometimes called water stick insects) are predatory, freshwater true bugs found throughout the world. Their raptorial front limbs are used for grasping prey, which includes other insects, tadpoles, and even small fish. They breathe air through a tail-like siphon on their rear end. Despite their almost exclusively aquatic lifestyle, they can and will fly, but do so rarely.
Photo 1 by zhongyankui, 2-3 by wenzel_sylvester, 4 by gijwans, 5-6 by Art Anker (shared with permission; do not remove credit or re-post!), 7 by vanremsen, 8 by josh_vandermeulen, 9 by diogoluiz, and 10 by hazelsnail
(via bowelflies)