creeping water bug

creeping water bug, Creeping water bug (Ambrysus mormon)William E. Ferguson any flat-backed, oval-shaped insect of the family Naucoridae (order Heteroptera), which numbers about 150 species. These small, dark bugs, commonly found in tropical regions, range between 5 and 16 millimetres (0.2 and 0.6 inch) and, when submerged, breathe from air stored under their wings.
