creeping water bug

creeping water bug, 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.

Creeping water bugs are usually seen swimming or creeping in quiet grassy or reedy waters. They prey on small aquatic organisms.