Monday, October 3, 2016

Great Golden Digger Wasp




"Within the insect order Hymenoptera, family Sphecidae, is the Sphex genus with over 130 recognized species and subspecies. One of the larger and more impressive thread-waisted is the Great Golden Digger Wasp or Sphex ichneumoneus. Aptly named, as the term "ichneumoneus" is Greek for tracker, these robust wasps are known for tracking their prey. Great Goldens are one-half to over an inch in length, though some sightings have reported seeing them as large as two inches. Great Goldens are easily spotted during the summer. Their black head and thorax are covered with short golden hair. Half of the back segment of their abdomen is also black with their front segment and legs a reddish-orange.

"Occurring in North America, Mexico, Central America, South America and the Caribbean, Great Goldens are usually seen in parks, gardens, fields and meadows - anywhere that is sunny, has compacted clay and sand, flower nectar for adults to feed on, and crickets, grasshoppers and katydids for their larvae. The adult wasps subside strictly on sap fluids and a variety of flower nectars that bloom during their flying time. Spotting them is one thing, but observing them can be dicey. Great Goldens do not linger around a bloom for very long and are quite wary of anything larger than they are. Fortunately, though they may look scary, these wasps are not aggressive unless handled and should be left alone. Great Goldens are solitary wasps, live independently and do not share in either nest maintenance or in the caring of their young.




"Between May and August, the female Great Golden, in preparation for egg laying, constructs as many as half a dozen nests. The building of, and provisions for, the nests is done in a concise, methodical manner, which she never deviates from. Rarely is there vegetation around the nests. Most sites are exposed to the sun in an open locale. The female begins digging, almost vertically, by cutting the earth with her mandibles. She walks about an inch backwards from the nesting site with a section of soil between her forelegs and head and flips the soil with her forelegs beneath her body, scattering it to the sides with her hindlegs.


"Great Golden nests have a cylinder shaped main tunnel that is one-half inch in diameter and four to six inches deep. From the main tunnel, she extends secondary tunnels that lead to individual larval cells where she will store anesthetized prey. The cells are broader than the tunnels and parallel to the soil. Once completed, she temporarily closes it after excavation by using the earth that remains by the nest entrance. The female throws it towards the entry with movements identical to those she made when she dug the nest.


"After constructing the burrow, she flies from the nesting area to open fields and hunts for any number of small locally available species of Orthoptera. Great Goldens hunt for crickets (Gryllidae), grasshoppers (Trimerotropis) and katydids (Tettigoniidae) to serve as a food source for her young. Upon capturing a suitable prey, the female Great Golden will paralyze it with toxins in her sting. If the prey is small, she flies it directly to the nest. If prey is too large to transport aerially, the wasp will walk with it across the ground. The prey is clasped beneath her body by grasping its antennas with her mandibles. Once the Great Golden reaches the opening of her nest, she sets the paralyzed insect down. Leaving the prey outside, she goes into the tunnel for inspection. When satisfied that all is well, she comes partially out from the nest and again grasps the prey's antennas pulling it backwards into the nest's interior where it is deposited in a cell with its head turned to the bottom.






"Though the prey is permanently paralyzed, it is able to eliminate feces and slightly move its antennas and mouthparts. Great Golden females close the nest each time prey is placed inside. When she re-enters for egg laying, she emits a set of buzzing sounds as she compacts the earth closing the entrance.

"After the Great Golden has dragged all her paralyzed prey into the nest hole, she lays one egg on each insect, placing it horizontally on the prey's thorax. The eggs are yellow, less than a 1/2 inch long and has a slightly curved cylindrical shape. They hatch within 2-to-3 days of oviposition, and without moving, they begin to feed on the prey's abdomen or at the junction of its leg. The feeding phase is very rapid. In one of the observed cases, the larva consumed even the more rigid parts of the prey's exoskeleton.


"Unfortunately, homeowners, who have these foraging wasps around their landscape and dig holes in their lawn, usually reach for a can of insecticide. Great Goldens are benign, do not defend their nests, are not aggressive and definitely do more good than harm. Hold that can for a moment and realize that like many other wasps, the Great Golden Digger Wasp is quite beneficial to both gardeners and farmers. So please leave them alone to do their job."**


**Text by Candice Hawkinson:  http://aggie-horticulture.tamu.edu/galveston/beneficials/beneficial-54_great_golden_digger_wasp.htm


All of these photos are mine, and I feel super lucky to have been able to witness it. This wasp built her nest in a sunny spot at the edge of our gravel driveway here in western Maine. Still hoping for a shot of one flying with a katydid in her arms!

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