This is the best for me. It's messy but it works. I got two dogs around that love to munch on the little critters...so the safest SUREST way to kill them is to fill up a glass with regular dish soap (about 2 TBL full) then the rest of the way with water. Just throw the water at them. I don't know if the soap suffocates them or what, but it works every time. If it's a large nest maybe use a bucket or several glasses of water.
Let me know how it goes!
"A Jackie of All Trades..."
civil engineer/dog owner/chef/drag racer a.k.a. "Hot Wheelz"/mechanic/artist/seamstress/drama queen/etc, etc, etc.