The Nature of Our Neighborhood:
The Beneficial Wasps of Fort Tryon Gardens
By Leslie Day
Coming into 295 Bennett the other morning I spotted a cicada sitting quietly on the brick of our building and I looked around to see if its archenemy – the cicada killer wasp – was nearby. Last year was a huge year for the 17-year “Magicicada” with millions erupting from the earth to morph into large winged insects that nibbled on tree leaves, laid their eggs in tree twigs, mated and died. Their eggs hatched and their larvae fell to earth, digging into the soil to quietly live on tree root sap for 17 years, before emerging once again to continue its cycle of being the longest-lived insect on earth.
The giant wasp, Sphecius speciocus, also known as the cicada killer, though it looks dangerous, is actually a beneficial insect that helps control the cicada population. You may have noticed these Buick-sized wasps flying around the Fort Tryon Gardens co-op apartment buildings from July through August. In fact, this year, management had a pest control company put out traps, though the traps were made to attract hornets, not Sphecius specioucus. When I voiced alarm and dismay over the thought that we would poison these important wasps, our hard working super, Manny, told me he thought that the traps wouldn’t work, and he was right! I saw dead flies but no dead cicada killers, at least outside 303 Bennett.
These giant wasps are not aggressive toward humans. The males have no stingers at all and are only interested in finding females. As you walk by them, they may fly over to you, but only to see if you are a female wasp. These are burrowing wasps, capable of digging a tunnel up to 20 inches deep and more than half an inch wide. The female digs by using her jaws to loosen the soil and her back legs to push the soil behind her as she backs out of the burrow. The dislodged dirt forms a mound around the tunnel entrance.
The female has a retractable stinger that she uses to paralyze cicadas, which she then carries to a nest cell within her burrow. (see video)
Once she has dragged the cicada into her nest, she inserts an egg into it. When the larva emerges it feeds on the cicada. Females determine what gender their eggs will be: if the egg is male she inserts one into the cicada. If the egg is female she leaves it two or three cicadas. Females are much larger than males and need more food as they develop.
Before my husband and I moved to Fort Tryon, we had lived on a houseboat on the Hudson River at the 79th Street Boat Basin for 36 years. It was in Riverside Park that I first encountered these amazing wasps. We moved to our apartment at 295 Bennett so that we could still feel close to nature: with views of the Manhattan schist cliffs, birds, trees, and flowers across the street, so close you feel you could reach out the window and touch all this beauty. However, when we moved away from the marina I was sure I would never see cicada killers again. The week we moved in, mid-August 2011, imagine my surprise when I walked out the door and saw these huge wasps, digging their tunnels, and going about their amazing lives.
Next summer, when the adults emerge from their burrows, don’t be alarmed, but rejoice in these winged neighbors who help keep our beautiful trees free of those leaf-nibbling cicadas.
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For more information on cicada killers, visit Prof. Chuck Holliday’s cicada killer page.