This might not be as obvious as it seems.
It would be easy to treat wasps like flies, and simply spray them with a can of Mortein. The trouble with this approach, however, is that the active ingredient in Mortein, and every other insecticide on the market, is a pyrethroid.
Pyrethroids are wonderful insecticides, in that they are effective killers of insects, which have very low human toxicity, but when it comes to wasps, they have a drawback.
That drawback is that the insects go through a hyperactive stage before they die. In other words, they don’t just drop dead as soon as you spray them.
When it comes to nasty things like wasps, this can be a problem for obvious reasons. What you want is something that will disable the wasps as soon as they are sprayed.
Fortunately, this can be done. We sometimes make the mistake of thinking that poisoning is the only way to kill an insect. Now if we think about it for a moment, we can see in the world around us that there are many ways that insects, animals, and people die.
That is, aside from poisoning there is suffocation, blunt force trauma, knives and guns, drowning, heart attacks, and so on.
And so it is with insects. And in this case, the best instant killer for a wasp (or a cockroach) is an adhesive of some kind.
An example would be hairspray. Hairspray, of course, contains adhesives for sticking the strands of your head together, specifically, gums and resins.
These gums and resins are dissolved in an alcohol base, so what happens when the wasp or cockroach gets sprayed is that the solvent attacks any mucous membranes (in just the same way that pure alcohol up your nose or in your eyes will sting). This has an instant disabling effect. On top of that, the alcohol has a freezing effect as it dries, and when it does dry they find that every orifice is covered with a suffocating layer of gum or resin.
Pretty gruesome when you think about it.
But any adhesive will do. The wasps who built their nest on a water feature outside my house met their demise with a can of Kwik Grip spray. I just walked up, plastered their nest with it, and the result was both spectacular and instantaneous. Every single wasp disabled and killed immediately.
Of course, the use of any adhesive will leave sticky stuff behind whatever you spray it, but outside that it is not of course a problem