Showing posts with label wasps. Show all posts
Showing posts with label wasps. Show all posts

Wednesday, January 21, 2026

Another Micro Mystery

One way that I find insects in winter is by scraping off paper wasp nests that have been abandoned by the past season’s generation of wasps, and placing the nests in a transparent container. What usually happens is that one or more kinds of insects will eventually emerge from these nests. Allow me to share one example.

Dibrachys sp.

I started collecting recent, abandoned paper wasp nests (Polistes metricus is the common species around our home here in Leavenworth, Kansas, USA) when I saw a social media post by Sloan Tomlinson (@thatwaspguy on Instagram). He had reared a type of small parasitoid wasp as a result: the eulophid wasp Elasmus polistis. That species is a parasitoid of the brood (larvae, pupae) of paper wasps. Cool. I could add another species to my home biodiversity list.

So many tiny wasps!

I was excited to find, in January of 2022, that this method had worked, as I saw tiny wasps running around inside the container with the old paper wasp nest. Photographing the little creatures, and then cropping those images, it became apparent that what I had was not what I expected. I was left with a mystery that took me awhile to solve, even though I’m fairly good at researching.

I eventually found a journal article chronicling a study of various parasitoids of paper wasps collected from nests in Missouri, the state immediately adjacent to Kansas. In fact, Leavenworth is right across the Missouri River from Missouri. One of the creatures listed was a wasp in the family Pteromalidae. They had only eighty-seven specimens, though. I was looking at hundreds by the time they finished emerging.

Male wasps attempting to mate with a female.

The species name given was Dibrachys cavus. More recently, it has been revealed to be a “species complex,” and has a new assigned name: Dibrachys microgastri. It represents one of *three* species, any one of which could potentially be my creature. Collectively, they are parasitoids of pretty much any insect with complete metamorphosis. That makes it difficult to determine exactly which one I have. Even placing a specimen under a microscope might not be enough magnification for these two-millimeter wasps.

Dibrachys is unusual for a single genus of wasps in having such a wide range of potential hosts. At least some species, or perhaps most, are hyperparasitoids of tachinid flies and braconid or ichneumon wasps that are themselves parasitoids of moth pupae. This makes me wonder if these minions are part of this puzzle that I documented in 2022.

I find unsolved mysteries intriguing, and delight in them even if I never reach any verifiable conclusion. There will always be *something* that defies explanation in the natural world.

This little cobweb weaver spider may have been making a killing, literally.

Sources:Gibson, Gary A.P., John T. Huber, and James B. Woolley (eds). 1997. Annotated Keys to the Genera of Nearctic Chalcidoidea (Hymenoptera). Ottawa, Ontario: NRC Research Press. 794 pp.
Peters, R.S. & Baur, H. 2011. A revision of the Dibrachys cavus species complex (Hymenoptera: Chalcidoidea: Pteromalidae). Zootaxa, 2937 (1), 1-30.
Whiteman, Noah K. and Brett H.P. Landwer. 2000. Parasitoids Reared From Polistes (Hymenoptera: Vespidae: Polistinae) Nests in Missouri, With a State Record of Elasmus polistis Burk (Hymenoptera: Elasmidae). J Kansas Ent Soc 73(3): 186-188.

Monday, June 9, 2025

Recent "Bug Eric" News

Bioblitz on the Snadon Tract of Coyne Prairie, Missouri, USA.

I was honored to be invited to be a guest on This Green Earth, a podcast, and NPR talk show hosted by KPCW in Park City, Utah, USA, last Tuesday, June 3. I spent a delightful twenty minutes or so with Claire Wiley and Christopher Cherniak, discussing wasps, and my book Wasps: The Astonishing Diversity of a Misunderstood Insect. If you would be interested in having me as a guest on your own podcast, please contact me via email: bugeric247ATgmailDOTcom. Thank you.

This past Saturday and Sunday, Heidi and I participated as group leaders for the annual prairie bioblitz organized by Missouri Prairie Foundation. This year it celebrated National Prairie Day at the Snadon Tract, a new addition to MPF's existing Coyne Prairie in Dade County, Missouri, USA. A future blog post will detail some of our insect and arachnid findings there.

Indian paintbrush flowers on the Snadon Tract of Coyne Prairie.

The bioblitz events of Missouri Prairie Foundation keep getting bigger and bigger. It is humbling to realize that a few attendees come specifically to meet myself and Heidi, and go on "bug walks" with us as we document the macrofauna. MPF is one of the most friendly and accomplished nonprofit organizations I have ever encountered, and I encourage my followers to consider membership or donations.

More personal traveling is on the horizon, but I will do my best to post notification of any public engagements. Meanwhile, the official publication date of my new book, Bugwatching: The Art, Joy, and Importance of Observing Insects is July 22. Please see the top of the sidebar if you wish to preorder. Thank you as always for your loyalty and support.

Thursday, August 22, 2024

A One Millimeter Mystery

Sometimes a minor disaster turns into something positive, like a fallen tree limb revealing a hidden relationship between a wasp, a fly, and a saw blade. All of this in the front yard of our house in Leavenworth, Kansas, USA.

Yikes!

Upon returning from a week-long road trip in late June that took us into Arkansas, southeast Missouri, and southern Illinois, we pulled up in front of our home to discover that a massive tree limb had broken off the ancient Pin Oak, miraculously landing between our house and the neighbor’s house, with no significant damage to either structure. This makes the third such incident since we moved here in May of 2021.

Ugh, I've got a big job ahead of me.

We do not own a chainsaw, so I started cutting off the smaller branches with a couple of manual saws that we have. The odor emanating from the cuts attracted several wood-boring beetles right away. Close behind them were parasitoid wasps looking to oviposit on the eggs or larvae of their beetle hosts. While this was entertaining, and resulted in adding a new longhorned beetle to our home list of animal life, a more intriguing scenario attracted my attention.

My saws bring all the wood-boring insects to our yard.

Awhile later, I noticed several minute black specks moving over the surface where I removed the branch. They had to be insects, but I could not tell what kind. I took a few photos, and was shocked to find they were miniscule wasps. Some had greatly elongated abdomens, others did not.

At least the long-bodied wasp is a Synopeas sp. platygastrid wasp.

I submitted a couple of photos to the Hymenopterists Forum, an interest group on Facebook, to solicit an identification from true expert specialists. They did not disappoint.Bob Zuparko suggested they might be in the family Platygastridae, and that was confirmed by Kendrick Fowler. He also suggested a genus, Synopeas, and subgenus Dolichotrypes. He wasn’t sure the wasp with the “normal” abdomen was even a male of the same thing. It might be something else entirely.

Fowler went on to explain that this is a known behavior, the attraction to freshly cut oak, and that the host is presumably some sort of fly in the gall midge family Cecidomyiidae. That floored me because until then I thought all gall midges attacked foliage and/or stems. Also, how did this behavior evolve? There weren’t saws of any kind until recently, in the evolutionary sense. Beavers?

I decided to dig a little deeper and discovered that there is a genus of gall midges that oviposits in this situation: Xylodiplosis. I went back out and looked at some of the branch stumps again. Amazingly, I managed to find a few gall midges laying eggs. They were much more difficult to photograph than the wasps, and not as numerous, either. Why the wasps arrived before their hosts is a mystery to me. Oh, and there is also Ledomyia, another genus of gall midge that lives in freshly cut wood like this. I’m honestly not positive which one I documented.

Female gall midge, probably Xylodiplosis sp., ovipositing.

It turns out that Xylodiplosis gall midges have all kinds of enemies. They are attacked by nematode worms (family Ektaphelenchidae), mites (family Tarsonemidae, tribe Pseudotaesonemoidini), even another kind of gall midge (Lestodiplosis xylodiplosuga). Most of the research on these has come out of Europe, by the way, so it may not apply here in North America.

Back to the wasps. Synopeas larvae do do not begin to develop until after the host gall midge larva leaves its lair in the xylem wood to pupate in the soil. The adult wasp emerges about fourteen days after the unparasitized adult of the host gall midge, according to one source (Rock and Jackson, 1985). In their findings, the rate of parasitism was about five percent, and that included another platygastrid wasp in the genus Leptacis.

In at least one of my photos of the wasps (first photo of them in this post), I can barely make out the short spine on the scutellum (top rear of thorax) that separates Synopeas from similar genera of platygastrids. Identification of species is not possible without examination of a specimen under high magnification. There are currently forty-four known species of Synopeas found in the Nearctic (North America more or less north of Central America). I will leave you to go farther down the research rabbit hole.

Sources: Awad, Jessica N. 2020. “Building a diagnostic framework for the genus Synopeas Forster (Hymenoptera: Platygastridae: Platygastrinae) based on reared specimens from Papua New Guinea.” Master of Science thesis, University of Florida.
Crawford, J.C. and J.C. Bradley. 1911.”A New Pelecinus-like Genus and Species of Platydateridae,” Proc. Ent. Soc. Wash. 13: 124-125.
Gagne, R.J. 1985. “Descriptions of new Nearctic Cecidomyiidae (Diptera) that live in xylem vessels of fresh-cut wood, and a review of Ledomyia (s. str.),” Proc. Ent. Soc. Wash. 87(1): 116-134.
Hooper, D.J. 1995. “Ektaphelenchoides winteri n. sp. (Nematoda: Ektaphelenchidae) from wood fly larvae Xylodiplosis sp. (Diptera: Cecidomyidae),” Fundamental and Applied Nematology 18(5): 465-470.
Khaustov, Alexander A., Arne Fjellberg, and Evert E. Lindquist. 2022. “A new genus and species of Pseudotarsonemoidini (Acari: Heterosstigmata: Tarsonemidae) associated with xylophagous gall midges in Norway,” Systematic and Applied Acarology 27(6): 1020-1034.
Rock, E.A. and D. Jackson. 1985. “The biology of xylophilic Cecidomyiidae (Diptera), Proc. Ent. Soc. Wash. 87(1): 135-141.
Skuhrava, M. and K. Dengler. 2001. “Lestodiplosis xylodiplosuga sp. n., a predator of Xylodiplosis sp. (Diptera: Cecidomyiidae): morphology of developmental stages, biology and behaviour,” Acta Societatis Zoologicae Bohemicae 65(1): 57-68.

Thursday, April 4, 2024

First Night of Blacklighting

Since I posted about my last night of blacklighting last year, it seems only fitting that I post about the first night of blacklighting this year. We had an unseasonably warm and humid night on March 31, 2024, so I put up a sheet and light in our fenced-in back yard here in Leavenworth, Kansas, USA. The effort turned up a handful of nice moths, and a couple of surprises.

Birch Dagger moth

A lovely and surprising moth was a freshly-minted Birch Dagger moth, Acronicta betulae. It looked like the front wings were made of two layers. Striking! This is a widespread eastern U.S. species, but eastern Kansas is at the western fringe of its range. We also do not have any River Birch, the host tree for the caterpillar, to my knowledge, so perhaps it is feeding on a different tree here.

Intractable Quaker moth

Another kind of owlet moth in the family Noctuidae that showed up was the Intractable Quaker. Ok, who makes up these names? The caterpillar of this moth is more straightforward: Four-lined Green Fruitworm. The scientific name of the species is Kocakina fidelis, but known formerly as Himella fidelis. This is another early-appearing eastern North American moth. The caterpillar stage feeds mostly on the leaves of oak, elm, and flowering crabapple, but is also known from hickory and cherry.

Distinct Quaker moth

The final noctuid of the night was the Distinct Quaker, Achatia distincta. It is a spring species ranging mostly east of the Great Plains, but with scattered records farther west. The caterpillar is a generalist feeder on most common deciduous trees, plus grape.

An expected species was an owlet moth in the family Erebidae, the Forage Looper, Caenurgina erechtea. It is abundant here locally, but is common throughout the U.S. and Canada. Caterpillars feed on grasses, clover, and alfalfa. Walking through your lawn will flush these moths during the day, especially if it has beeen awhile since you mowed.

Common Gray moth(?) male

One geometer moth was tucked in a fold in the sheet: what I believe to be a Common Gray, Anavitrinella pampinaria. The lack of clear markings makes identification even more difficult than usual, but the early spring flight period is typical. This is another widespread species across the continent. The super-slender caterpillars (inchworms) are known to feed on clover, ash, elm, willow, pear, and apple.

Lucerne Moth

One moth of the family Crambidae flew to the edge of the sheet. The Lucerne Moth, Nomophila nearctica, is found nearly everywhere in North America, farther north in the west. Its narrow silhouette makes this moth one of the easiest to recognize. The caterpillars feed on a wide variety of grasses and sprawlilng legumes like clover and alfalfa.

Smaller moths were more common, including a single individual of the Red-banded Leafroller Moth, Argyrotaenia velutinana. This species of the family Tortricidae is common east of the Rocky Mountains, from Louisiana to Saskatchewan. There is hardly any foliage and fruit that is not on the menu for the caterpillar stage, and it is an occasional pest in apple orchards.

Unidentified tortricid moth
Maple Twig Borer Moth

A couple of other tortricids defy identification, and I am rusty at photography after the winter hiatus. Wait, one of them was confirmed as the Maple Twig Borer Moth, Proteoteras aesculana. As the name suggests, it occurs where maple trees are found, and the caterpillar stage tunnels in the twigs and petioles, and seeds of the host tree.

Twirler moth, genus Chinodes?

Finally, there was a solitary little twirler moth, family Gelechiidae, that I figure is one of the 190 North American species of Chinodes.

Ichneumon wasp, Ophion sp.

A bit surprising was the diversity of wasps present at the blacklight. Ichneumonid wasps in the genus Ophion are regular visitors, as they are nocturnal, but a beautiful Rhyssella nitida also showed up.

Ichneumon wasp, Rhyssella nitida

This is a diurnal insect. The female uses her long ovipositor to drill into logs and dead trees to reach the larva of its host, wood-wasps in the genus Xiphydria. She lays a single egg on the grub, and the larva that hatches feeds as an external parasitoid, eventually killing the wood-wasp larva.

Braconid wasp
Braconid wasp, Phanerotoma sp?
Braconid wasp

Wasps in the family Braconidae, closely related to ichneumons, also flew in. They are almost impossible to identify from images of living specimens, but their diversity and abundance is encouraging in an age of insect decline.

A particularly attractive non-biting midge, tribe Macropelopiini
Typical non-biting midge, tribe Chironomini

As expected, flies were the most diverse insects on the sheet. Non-biting midges in the family Chironomidae can be found almost year round. They are usually asssumed to be mosquitoes, and they are certainly mosquito-like in appearance, but totally harmless. Most live in aquatic habitats in the larval stage, where they are usually scavengers.

One of the larger gall midges I've seen

Early spring is the time for gall midges in the family Cecidomyiidae. These small, delicate flies are recognized in part by the reduced number of veins in their wings, and their usually long antennae. They are tiny enough that they can account for the most commonly found insects indoors, accumulating in light fixtures and on windowsills.

Fungus gnat

Fungus gnats are also springtime flies, of the family Mycetophilidae. They look like mosquitoes, too, but their legs usually sport long spines, at least at the tip of the tibia segment. The larvae of many species occur in mushrooms, and are identified by their black heads. The adults of some species pollinate the flowers of Jack-in-the-Pulpit, but frequently die after becoming trapped in the corolla.

Leaf miner fly, Cerodontha sp.

More obviously fly-like were little leaf miner flies, in the genus Cerodontha, family Agromyzidae. Their larvae bore between the layers of grassblades, and leaves of sedges and rushes. We have both grasses and sedges in our back yard, so that tracks. Identifying insects is often a matter of putting different clues together and seeing what shakes out.

Shiny Blue Blow Fly, Cynomya cadaverina

A big, bumbling blow fly bounced around the light, too, and it was difficult to get an image of it. I think it was a Cynomya cadaverina. No dead bodies in the backyard, so its presence is a mystery.

Birch Catkin Bug

The other mystery was the appearance of a Birch Catkin Bug, Kleidocerys resedae, a tiny member of the seed bug family Lygaeidae. As in the case of the Birch Dagger Moth, the absence of birch trees raises questions about what these bugs are eating.

All thirty insects that I documented can be found on iNaturalist here. It has been windy and cooler this last week, so I'm not sure when I'll put the light out again, but I look forward to doing so. Weather permitting, I will at least try again during the City Nature Challenge, April 26-29. Check and see if your town is registered for the event. Happy bugwatching to you in any event.

Friday, March 1, 2024

How We Can Stop Hating Wasps

Recent studies have shown that wasps are among the most loathed of all insects. Consequently, much time and money is wasted on trying to eradicate them, especially by homeowners. Let’s consider why we have the attitudes we do, and how we can achieve coexistence with wasps.

A trio of Western Yellowjakcet workers dispatches a pest caterpillar.

Why do we hate wasps?

There are three main reasons wasps evoke fear and loathing.

  • The sting. Females of some species can inflict painful stings on us tender humans. This is occasionally for self-defense, but mostly in defense of a nest full of immobile and otherwise vulnerable eggs, larvae, and pupae inside a nest. Only social wasps will bother us this way.
  • Narrow definition of “wasp.” Most people equate the word “wasp” with “hornet,” “yellowjacket,” or “paper wasp.” All of these are social wasps, the ones most abundant in urban and suburban settings, and by far the ones we have the most negative encounters with. Some people recognize other kinds of wasps, particularly mud daubers, but consider their nests unsightly, a nuisance, or a potential threat. In reality, the overwhelming majority of wasps are solitary, like mud daubers, each female making her own nest, or using a host animal or plant in situ. Most wasps cannot sting people. Many cannot sting at all. Most are tiny, only ten millimeters or less in length.
  • Social wasps exploit our habits and weaknesses. Yellowjackets (including the Bald-faced “Hornet,” and paper wasps make their nests in and around our homes and buildings. This is because our architecture mimics the cliff faces, rock overhangs, and natural hollows where they nest “in the wild.” A few yellowjacket species are scavengers, and your barbecue or picnic resembles an abandoned animal carcass that can be exploited. The wasps take protein matter back to the nest to feed their growing larval siblings. Meanwhile, your open soda or beer container offers sugary carbohydrates the adult wasps need to fuel their flight muscles. We like to think we are masters of our domain, or at least our private property, and wasps defy that desire with maddening efficiency.

Most wasps, like this "fairyfly," are tiny, solitary, and don't sting people.

Benefits of Tolerating Wasps

Positive outcomes from tolerating wasps, or even accommodating them, far outweigh any perceived benefits of eradication or control, excepting rare cases where you or another family member has hypersensitivity to insect venom, and there is demonstrable risk of a life-threatening incident.

  • Saving money on products or services. This point is seldom made when arguing against the use of DIY pest control products, or the employment of professional pest control services, but it can be of profound financial consideration. Prevention is easier and more effective. More on that in a moment.
  • Wasps are a pest control service. Most social wasps, even those that scavenge occasionally, are predatory on insects that are problematic in our yards, gardens, barns, and sheds. Solitary wasps are parasitoids of even more species that can be truly pestiferous. Among the hosts for wasps are caterpillars that eat garden plants, aphids that suck plant sap, flies that can potentially spread bacteria, cockroaches both outdoors and indoors, and spiders. There is scarcely any terrestrial arthropod that is not host to at least one wasp species.
  • Wasps are pollinators. Technically, most wasps are “flower visitors,” coming to blossoms for nectar to fuel their flight muscles. They still effect pollination services, and there are some species in western North America that are obligate pollinators of certain wildflowers.
  • Wasps dispose of animal carcasses. Those scavenging yellowjackets make quick work of the remains of small animal carcasses that vultures and other vertebrate scavengers ignore or cannot find. This prevents the accumulation of decaying animal matter, lessens risks to human health from problematic bacteria, and prevents explosions of filth flies that would otherwise use those dead animal resources.
  • Wasps are a source of fascination and intrigue. Wasps can be easily and safely observed as they go about their activities of host-seeking, flower-visiting, and nest-making. You will be surprised by how many wasp species are living in obscurity in your yard and garden. Watching them will reveal amazing relationships with many other organisms.

Paper wasp nests can be safely observed and offer hours of fascination.

How do we get along?

We can prevent most negative encounters with wasps by taking a few precautions. It will literally save you physical pain and financial discomfort.

  • Learn wasp body language. Paper wasps, the ones that make uncovered paper combs under eaves, in door and window frames, and elsewhere, are usually amicable neighbors. If you do approach a nest too closely, one or more wasps will stand on tiptoe and flare their wings. This means “back off.” You risk being stung if you ignore that warning.
  • Inspect your yard regularly. Too often, underground yellowjacket nests, or those above ground, hidden in shrubs or rock walls, are not discovered until the lawnmower runs over one, or the hedge trimmer triggers an attack. Inspect your property thoroughly, including playground equipment, before using tools, or otherwise causing any strong vibration in the vicinity of a social wasp nest. It may take a little patience and keen observation to note the streams of wasps coming and going regularly from a specific location. Your kids may see them before you do.
  • Serve beverages outdoors in clear glass or plastic.
  • Unattended beverages that are sweet or fermented will attract yellowjackets and other wasps that may crawl inside the container. Cans and opaque bottles mean that you will not notice a wasp inside. A sting to the tongue or throat can be a life-threatening experience regardless of whether you are allergic to stings.
  • Cover food served outdoors. When not serving yourself or others, cover meats and sweets at the outdoor gathering. You can also set out a small, exposed plate of meat a good distance away from the serving table, to draw yellowjackets away.
  • Seal cracks and crevices. To prevent wasps from nesting indoors, or seeking shelter in the winter, seal cracks and crevices. Mend holes in, or replace, window screens. Screen the attic vent with fine mesh. Replace worn weatherstripping around doors. This will help save on heating and cooling costs, too.
  • Learn to recognize solitary wasps. Many wasps that are solitary may behave as if they are social. A large number of wasps flying low over your lawn are likely male wasps looking for females that have yet to emerge from the ground. An ominous gathering of iridescent blue mud daubers in a door frame at dusk means that males are bedding down for the night in a large group. Male wasps do not sting. Cicada killers are huge wasps, but solitary. Females may nest close together, making them appear social. Males keep watch over them and may fly “aggressively” to chase away any and all intruders. It is all bluff.

More information about wasps can be found in this blog, in my book Wasps: The Astonishing Diversity of a Misunderstood Insect, and elsewhere. Online, the most reliable sources remain college, university, and museum websites with a “.edu” or “.org” suffix in the URL. Thank you in advance for sharing a link to this post in social media, neighborhood groups, and other outlets.

A solitary thread-waisted wasp with a caterpillar she stung into paralysis. It will be food for her single larval offspring at the bottom of an underground burrow.

Sources: Schmack, Juila M., Monika Egerer, Susan Karlebowski, Astrid E. Neumann, and Ulrike Sturm. 2024. “Overlooked and misunderstood: how urban community gardeners perceive social wasps and their ecosystem functions,” Journal of Insect Conservation.

Thursday, January 12, 2023

Wasp Webinar Presentation to Athol Bird & Nature Club

Last night I presented a webinar on "Wasps: The Astonishing Diversity of a Misunderstood Insect" to the Athol Bird & Nature Club. Here is the embedded recording from Youtube if you would like to view it. I cannot guarantee an indefinite duration for the link. Thank you.

Wednesday, December 7, 2022

A Potential New Host Record for Calliephialtes grapholithae (Hymenoptera: Ichneumonidae) from a Paper Wasp nest (Hymenoptera: Vespidae: Polistes metricus)

Adult female ichneumon wasp, Calliephialtes grapholithae

It started out innocently enough. Back in 2021, a Facebook post by Sloan Tomlinson (@thatwaspguy on Twitter) caught my attention. He had reared small parasitoid wasps, Elasmus polistis, from an abandoned paper wasp nest that he had contained. I messaged him to learn more, and then followed his suggestion to try this myself.

Nest of Polistes metricus from 2022

We had a nest of the Metric Paper Wasp, Polistes metricus, in a corner of the recessed frame of our back porch doors (French doors) at our home in Leavenworth, Kansas, USA. After the wasps left, I cut down the nest and placed it into a plastic container. Shortly thereafter, in about mid-November, a large number of small parasitoid wasps emerged that were not the same as those that Sloan Tomlinson had reared out. That is a separate mystery from the one I am documenting today.

This year, 2022, we had two Polistes metricus nests, one in each corner of the door frame. One succeeded better than the other by a substantial margin, and I repeated the exercise of cutting down the larger nest and containing it in late autumn. Besides the large number of tiny, metallic parasitoid wasps, I got a shocking surprise.

My partner, Heidi, and I went on a vacation in late October. When we returned, I was amazed to find a live female ichneumon wasp, one nearly deceased male, and one deceased male, inside the container with the Polistes nest. The insect was not one of the species that is a known parasitoid of paper wasps. I was able to identify it as Calliephialtes grapholithae, but that made no contextual sense. All of the known hosts for that species are caterpillars of moths.

Adult males of Calliephialtes grapholithae

Previously recorded hosts for C. grapholithae include larvae of the following Lepidoptera: Acrobasis betulella, (formerly A. hebescella), A. juglandis, A. rubrifasciella (recorded as A. nibrifasciella (Pyralidae: Phycitinae); Carmenta texana (Sesiidae: Sesiinae); Cydia caryana (recorded as Laspeyresia caryana, the Hickory Shuckworm, Tortricidae: Olethreutinae); Meskea dyspteraria (Thyrididae: Siculodinae); Periploca ceanothiella (recorded as Stagmatophora ceanothiella, Cosmopterigidae: Chrysopeleiinae); Thyridopteryx ephemeraeformis (Psychidae: Oiketicinae); Megalopyge opercularis, the Evergreen Bagworm (Megalopygidae). Most of these taxa represent a “concealed host,” such as the Evergreen Bagworm and Hickory Shuckworm.

The only way the association of C. grapholithae with paper wasps can be made is if there is a moth larva involved in some fashion. It so happens that there is. The Sooty-winged Chalcoela, Chalcoela iphitalis, is such a moth (Crambidae: Glaphyriinae). The caterpillar stage is predatory on the larvae of Polistes wasps, inside their nests. Webbing spun by the caterpillars is a clue to their presence. Apparently, the adult female moth approaches the nest at night, when the adult wasps are less alert. Still, she may lay her eggs on the back of the nest, and let her tiny larval offspring find their way into a cell.

Caterpillar of Chalcoela iphitalis from paper wasp nest

Sure enough, I happened to notice one of these moth caterpillars, strikingly similar to a paper wasp larva, in the bottom of the container with the nest and its other associates. There is little doubt in my mind that C. iphitalis is a host for the ichneumon wasp Calliephialtes grapholithae. The pattern of this wasp seeking concealed hosts fits, though how the wasp navigates a well-defended nest of paper wasps is beyond my imagination. I am hoping that such an infiltration can be documented, or that someone else will independently rear the ichneumon from a paper wasp nest. Until that time, I cannot assert, unequivocally, the host relationship.

Adult Chalcoela iphitalis moth

I also wonder if the sever drought experienced by eastern Kansas this past summer had anything to do with the proliferation of the moths that plague the paper wasps. I noticed more than usual. One of the two nests almost failed completely, though one of the foundress wasps may have died prematurely, slowing the nest’s rate of growth, eventually halting it.

Much remains to be discovered about even the most common of insects, especially when it comes to ecological relationships to other species. I urge my readers to undertake what observations and experiments they can to further enlighten our understanding of the natural world.

Sources: Carlson, Robert W. “Database of Hymenoptera in America north of Mexico,” Discover Life
Hoskins, Jonathan. 2021. “Species Calliephialtes grapholithae,” Bugguide.net
McCormac, Jim. 2017. “Wasp-eating moth fills rare niche,” Ohio Birds and Biodiversity
Calliephialtes grapholithae,” iNaturalist.org