Badger Tracks

By Anita Carpenter

A Wasp in the Hand

My early morning walks often reveal Mother Nature's secrets if I just pause to look and listen.

I was strolling along the Oshkosh Riverwalk in late July when I spotted a good-sized insect resting on the path. From a distance, I wondered if it was a mayfly because its wings were held upright over its back. As I approached, I realized this insect was not a mayfly but something I had never seen before.

The intriguing insect seemed docile, so I gently picked it up by its wings and placed it on my hand. This large, delicate, shiny black insect was about 2-1/2 inches long with 2 long, black, thread-like antennae. Its head and thorax measured about 1/2 inch long and 1/4 inch wide. However, its shiny black abdomen, which had 6 segments and looked like it had a stinger on its tip, was 5 times its body length--about 2 inches.

Eventually, the insect tired of my hand, took flight, flew slowly and weakly, and settled on the ground.

My challenge was trying to identify this insect. I paged through my entomology textbook in the chapter devoted to the order Hymenoptera, which includes the ants, bees, and wasps. Lo and behold, this wasp was highlighted with a drawing. A unique and fascinating insect was about to be revealed.

This wasp is classified in the insect order Hymenoptera, family Pelecinidae, genus Pelecinus. Its scientific name is Pelecinus polyturator. It lacks a common name but has been referred to as the American Pelecinid Wasp. Interestingly, this wasp is the ONLY member or species in this genus in the United States. It is rare to have only one species in a genus classification.

Female Pelecinid wasps measure 2-1/2 inches long. Males are smaller measuring about 1 inch. Males in the southern United States are common whereas males in our northern regions are rare. Because of the scarcity of males, "northern" females will reproduce parthenogenically, which means that they do not require male fertilization to reproduce. Parthenogenesis is also fairly rare in the insect world.

Another unique feature is that Pelecinid wasps are parasitoids, which is defined as insects that parasitize their prey. Pelecinid wasps parasitize the underground grubs of June beetles. The wasp's skinny abdomen is neither a stinger nor a tail but is highly modified for egg laying. Even though the "stinger" may look ominous, Pelecinid wasps cannot sting.

June beetles bury their eggs in the soil. Their eggs hatch into grubs, which feed for 3 years underground, dining on plant roots before molting and emerging as adult June beetles.

When a Pelecinid wasp detects a subterranean June beetle grub, she inserts her abdomen into the soil and into the grub to deposit one egg. When the wasp egg hatches, the larva feeds on the June beetle grub. How a Pelecinid wasp detects the presence of an underground grub and how she determines if the grub is actually a June beetle grub is unknown.

Eventually, the wasp larva molts into an adult wasp, which emerges the following August into September. It would be interesting if we could actually witness what happens underground.

Pelecinid wasps live in sparse woodlands, woodland edges, and gardens. The wasps tend to stay low to the ground. The wasps may be found on flowers as adults dine on nectar.

I was excited to have discovered this insect with its unique and interesting life cycle. I hope everyone has the opportunity to see one someday.

September-October Newsletter 2025