Did a web search on these insects. Have them in my pool after rains & whenever I forget/don't treat it regularly. Apparently they fly & live in water.
Backswimmers and water boatmen are members of the order Hemiptera. The most noticeable difference between the two is that water boatmen swim on their tummies and backswimmers donâ€™t. On closer inspection, the backswimmers have a segmented, sharply pointed beak admirably suited for piercing the bodies of their prey. Water boatmen, being not strictly carnivores, have a kinder, gentler rounded beak. Both bugs can and will, however, draw blood from the relatively soft flesh of a human being.
Haven't found any way to actually kill them yet, but I would certainly not swim with them..last summer I got bit by something in the pool & I am pretty sure it was one of these little bugs & it hurt & got very swollen & sore!