I had a chain of toad eggs in my "cement pond" and there were a family of these bugs congregated around them. (It seemed some had eggs in their pinchers!) I looked at your sight and found them to be water scorpions. One was about 4 inches long so I put it aside for a photo session. My question is, "Do these guys eat toad eggs?"
This is the second image of a Water Scorpion in the genus Ranatra we received today. The first was from Georgia and yours is from parts unknown. We believe that Water Scorpions might prefer moving prey, but your observation indicates that they may eat toad eggs.