Giant Water Bugs (Order Hemiptera; Family Belostomatidae)

Ferocious Water Bug-  Hillsboro, Oregon

Note wings of Adult.

Ferocious Water Bug (Abedus sp.)-  Arizona

Although this isn't the largest species in the US, these Giant Water Bugs are formidable obstacles for tadpoles, minnows, and other small aquatic animals.  This species is common in many parts of Arizona.  A related species in the Eastern US has the nickname "Toe-biter", given by unfortunate victims of its bite.  That species reaches up to 3 inches.  Like other Hemipterans, Giant Water Bugs feed via a proboscis; a beaklike tube about 1/3 of an inch long!  Most interestingly, they have the ability to hold their breath for fairly long periods of time.  At the surface, the extend 2 small opening at the tips of their abdomens.  Air is taken in, and stored within the abdomen.  In the middle picture below, small air bubbles are visible through the transparent underside of the abdomen.

Note absence of wings meaning it is not yet mature.

Giant Water Bug (Lethocerus americanus)

Giant Water Bugs reach 2-3 inches, and are called toe-biters in many parts of the South-East USA.