To keep the nest from re-generating. Buy a box of moth balls. Take 1/2 the box and dump it into a nylon stocking. I have some hidden in my truck if you need borrow some. Make a nylon sock full of 1/2 box, tie the stocking off in a knot, then hang it from a nail right near where the nest formed outside. Guarantee, they will not return. Promise.......trust me, I used to sell cars.

Naw, really, it works!