I have a clear memory from childhood, at five or six years old, of my father running across the lawn in his boots and his cowboy hat, yelling at the top of his lungs. He was carrying a can of wasp nest spray in his hand, and he was being was chased by a big cloud of wasps.
The only thing I learned from this scene was to fear wasps, and that was an unfortunate lesson. It took me a long time to realize that wasps are highly beneficial in the garden.
Wasps eat an enormous amount of caterpillars and other garden pests. The wasps from a single small nest can quickly eliminate an entire pound of insects from a backyard garden–and that is a lot of garden pests you will never have to worry about.
Wasps patrol among the plants hunting. When a wasp sees a caterpillar, the wasp attacks and stings the caterpillar to paralyze it. Then the wasp picks up the caterpillar, flies it back to the nest, and stuffs the caterpillar into the holes of the comb. The queen lays her eggs inside the caterpillars, and the baby wasps eat their way out.
Mud daubers only eat spiders, and some mud daubers species only eat brown recluse or black widow spiders. The mud dauber paralyzes the spider, picks it up and flies or drags it back to the nest, and then stuffs the still-living spider into one of the chambers. The mud dauber babies move through each chamber of the nest and first eat the legs of the spiders, to keep them alive longer, then go back and eat the spider heads, then the bodies.
It is best to let mud daubers do their work, because there is no chemical insecticide as effective as mud daubers at controlling the spider population around your home.
In every generation of wasps, only a few of the females, the ladies-in-waiting, survive the year. They hibernate in cracks and crevices during the winter and emerge in the spring to build new nests. If you destroy a nest and kill these ladies-in-waiting, your pest population will get far out of control long before the wasps can repopulate and help you in the garden. Wasps never re-use their nests, so wait till autumn when the wasps are gone, if you want to clear out old nests.
To attract wasps to your garden, all you need to do is leave their nests alone, unless the nest is in a doorway or high-traffic area. Nobody wants a wasp sting, but the truth is that wasps rarely attack, unless someone is bothering their nest, as my father can certainly tell you. And Dad can’t run as fast as he could in the old days, so now he leaves the wasps alone—and that suits me just fine.
On our farm, we encourage a healthy wasp population, and that is one of the reasons we never have to use toxic pesticides in our gardens. In fact, these days, I am more concerned about seeing a can of wasp nest spray, than I am about the wasps.