Like a road crew on Interstate 80, the Great Golden Digger Wasps turn my flagstone garden path into a construction zone each summer.
But these bugs don’t need a bulldozer to move a lot of dirt.
Great Golden Digger Wasps show up in my garden every June, and remain for the next couple of months. While unsuspecting visitors to my garden may be wary of the large, buzzing insects, I have learned to coexist peacefully with them.
Other than piles of sand and dime-sized holes along the pathway, the Great Golden Digger Wasp does far more good than harm in the garden. And to humans and pets, the predatory wasp is virtually harmless.
Indeed, the Great Golden Digger Wasp is one of the hardest working bugs in the garden.
The Great Golden Digger Wasp
The Great Golden Digger Wasp is a member of the thread-waisted wasp family (Sphecidae), so named for the wasps’ cinched waists. There are more than 130 species of digger wasps (Sphex genus) in the Sphecidae family, and the Great Golden Digger Wasp (Sphex ichneumoneus) is one of the largest of all.
They are related to Mud Daubers, Sand Wasps, and Giant Cicada Killer Wasps.
The Great Golden Digger Wasp measures more than an inch in length. The wasp has a black head, orange and black body, orange legs, and iridescent amber wings. Short, golden hairs covers its head and thorax.
A solitary wasp
Unlike social wasps, which live commune-style with a queen that lays eggs and non-reproducing minions that handle the hard labor, digger wasps are solitary creatures. Each adult female Great Golden Digger Wasp works by herself to build and provision underground nests.
Although they work independently, multiple females may nest in the same general vicinity if conditions are right. They prefer sandy soil, an open, sunny area, and nearby vegetation where they can find their prey – grasshoppers, katydids, and crickets.
The flagstone path in my garden meets all of these requirements and serves as a nesting ground for dozens of Great Golden Digger Wasps each summer.
Unfortunately, social wasps – like yellow jackets and hornets – give all wasps a bad name. Solitary wasps like the Great Golden Digger Wasp are virtually harmless. They do not guard their nests and are not aggressive towards humans. Females are equipped with stingers but use them only on their prey, although a rare sting to a human may occur if the wasp is grabbed or stepped on. Male wasps may act aggressive, but they have no stingers and can do no harm.
The job of a Great Golden Digger Wasp
When an adult Great Golden Digger Wasp emerges from the underground nest where it hatched the previous summer, it has but one job to do: To reproduce.
For a male wasp, that simply means finding a mate. The female, on the other hand, will spend her short life engaged in the methodical building and provisioning of a half dozen or so nests. She will never deviate from a process that is hardwired in her genes.
First, she excavates a tunnel by digging straight down, using her mandibles to cut the earth. She clears dirt as she works by pulling it out backwards in piles between her head and forelegs. She scatters the dirt behind her and to the side using her hindlegs, creating a U-shaped pile around a dime-sized hole.
Off the main tunnel, which is four to six inches deep, the wasp builds secondary tunnels leading to individual nesting chambers. When the nest is complete, she piles dirt on top of the tunnel entrance to create a barricade while she goes off to hunt.
A parasitoidal wasp
The female Great Golden Digger Wasp’s next job is to provision the nest. She flies out from the nesting area to hunt for grasshoppers, katydids, and crickets. She is a parasitoidal wasp, meaning her prey will serve as a food source for her offspring.
When the wasp hunts, she stings her prey and releases paralyzing venom. She transports the paralyzed insect back to her nest by air – if it is light enough to fly with – or by dragging it across the ground by its antennas. On the way, she may have to fend off robins, sparrows, and other birds intent on stealing the insect from her.
Upon returning to the nest, the wasp drops her prey outside entrance while she reopens and inspects the tunnel. She then drags her still-paralyzed victim to a nesting chamber, and lays one egg on top of it.
When she leaves, she closes up the nesting chamber behind her. She will not return.
A Great Golden Digger Wasp provisioning her nest:
The wasp’s egg will hatch in two or three days, and the wasp larva will devour its still-paralyzed host alive. (I don’t like to think about this part too much – poor grasshopper.)
Over the fall and winter, the wasp larva will undergo a complete metamorphosis. It will emerge in June as an adult and begin the process all over again.
The Great Golden Digger Wasp: A beneficial bug in the garden
The first reaction of a gardener who confronts a large, intimidating-looking Great Golden Digger Wasp may be to grab a can of bug spray. Don’t do it! Not only are these bugs harmless to humans, they provide many benefits to the garden.
Adult wasps – both male and female – pollinate plants by feeding on flower nectar. Female wasps prey on grasshoppers and similar pests that otherwise cause a lot of damage to vegetable and ornamental plants in the garden. And by digging holes in the ground, the wasps help to aerate the soil and improve drainage.
So if you are lucky enough to encounter a Great Golden Digger Wasp in your garden, leave her alone. She’s working hard.
Want to learn more about the insects in your garden? Check out this good bug/bad bug field guide by clicking on the image below:
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