Moved from ID Request to new species page. The banded legs seen in the other photo's ventral view are characteristic of L. uhleri.

This is an adult giant water bug in the genus Lethocerus. They are also known as "electric light bugs" because they are attracted to lights at night. Obviously, adults can fly, but they often get 'stranded' on land, and are discovered the next morning....These insects are predators and bite with a sharp proboscis, so it is a good thing you managed not to get bitten. In nature, they eat other aquatic insects, and small vertebrates including frogs, fish, salamanders, even snakes.