Get a good cat and let nature's food chain do the rest. Three or four cats would let them know your yard isn't a good place to light & set.
It would be better than opening yourself to any legal problems from using an air rifle or other firearm in a populated area.
"To preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them." -Richard Henry Lee, Virginia delegate to the Continental Congress, initiator of the Declaration of Independence, and member of the first Senate, which passed the Bill of Rights.