Roundup kills weeds - and wasps!!! Never knew that 'til today. Was spraying weeds along the backside of my fence, where a vacant lot is overgrown, and came across two wasp nests. Sprayed several of them that were getting to close for my comfort. Then I started noticing those that got hit with a decent amount would land on a fence pole or weed and looked lethargic. So I'd hit 'em again with a stream of Roundup, and then within seconds - dead. I hate wasps. HATE them I tell you. So I was giggling pretty good at my discovery.