Daniel, I had a mantis in my tank a few months ago. If yours was snapping you would definitely hear it. I tried a few different traps, all to no avail. I caught everything but the mantis. It would look into the traps, but would not go in. Finally my wife a friend and i spent a day with some bamboo skewers and chased the bugger into a net and snatched him out. In my wife's opinion it was the most excitement she has gotten out of the tank. good luck....evan