It appears to be a type of Whirligig Beetle or another type of water beetle. Since you are in a wet area, they could be there in a puddle or other water source. They do not bore into trees and there isn't any control that needs to be done, they are harmless. The frass on the hosta leaf could be from something else.

Let us know if you have further questions with this. 

Emily

HI, 

The photos are a bit blurry so its difficult to say for sure if it is a carpenter ant or another type. Are you finding them inside? If it is a carpenter ant, they would be more attracted to wood.

Before spraying for anything, you should definitely make sure you know what it is. See if you can get one of the insects and freeze it in a sandwich bag then try to take a clear photo. You can also refer to our webpage(s) to read about and compare characteristics: 

https://extension.umd.edu/resource/carpenter-ants

https://extension.umd.edu/resource/termites

If you do an internet search for homemade Borax ant traps, you could bait them too and see if there is an abundance in population. Some will die in the solution and others will bring back some sugar to the potential nest and end up killing the other ants. If you have pets or small children, just be cautious that they don't get into the solution. 

If you would like to send in additional photos, you can attach them to this message. 

Emily