Our cedar tree, already stressed from too many hot/dry summers, now has carpenter ants. Is there a way to kill them off without either further damaging the tree or poisoning wildlife? We have deer wander through regularly and a skunk family next from door that has done some digging near the tree. I'm concerned not only about the tree, but about where the carpenter ants might decide to dine next. . . . If there is no ideal answer, what comes closest to being the least harmful method of dealing with them? (I will also note that the ferns look good because this year I'm finally hand watering them once a week - I lost several in previous summers.)