Parasites or Hitchhikers? Mites Found on Ceraphronoids

Ceraphronoidea is a superfamily of parasitoid wasps that occurs worldwide, yet little is known about the life history of this group. The superfamily includes both ecto- and endoparasitoids, sometimes within the same genus (e.g. Dendrocerus)1,2,3. Though ceraphronoids have been reported as parasitoids of at least nine different orders of insects 39, there are no reported parasites or parasitoids of any ceraphronoids to date. There is very little known about how ceraphronoids even interact with invertebrates other than their hosts.

While photographing specimens at the National Museum of Natural History (USNM) in Washington, D.C., I found a tiny mite clinging to the metasoma of the type specimen of Ceraphron carinatus. I found a similar mite on the metasoma of another type specimen, Conostigmus schwarzi.

Female type specimen of Ceraphron carinatus at the National Museum of Natural History (USNM) in Washington D.C., USA, with an astigmatid mite attached to the metasoma. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

I sent images to the Penn State Insect Identification Lab Director, Dr. Mike Skvarla, who recognized them as a type of mite belonging to the group Astigmata. One unique feature of this group is that many are asexual. “They’re diversifying without sexual reproduction,” Dr. Skvarla says, “but multiple lineages have also re-evolved sexual reproduction after it was lost.”

Dr. Skvarla referred me to Astigmata specialist Dr. Barry O’Connor, Professor & Curator of Insects and Arachnids at the University of Michigan. Dr. O’Connor recognized the mites as deutonymphs in the family Acaridae. As mites mature from larvae to adult, they go through three nymph stages—protonymph, deutonymph and tritonymph.

What are these mites, and what do they do? Do these mites feed upon the wasps, much in the same way that ticks feed upon deer and humans?

Not in this case.

While there are a few highly specialized parasites in the group, most acarids are actually fungivores or detritovores. In many Astigmata, the deutonymph life stage actually lacks mouth parts and cannot feed. Instead, these deutonymphs are phoretic.

Phoresy is a type of symbiotic interaction between different species, where the phoront or symbiont relies on a host to transport it from one place to another. It is a commensal type of relationship in that it benefits the mite and does not harm the wasp.

Female type specimen of Conostigmus schwarzi at the National Museum of Natural History (USNM) in Washington D.C., USA, with an astigmatid mite attached to the metasoma. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

In Astigmata, the phoretic deutonymph stage is specialized for dispersal. These deutonymphs are nothing more than hitchhikers, catching a ride on the wasps to move between different habitat patches.

Some deutonymphs are generalists in that they are found on many different types of insects, but others are specialists and rely on certain insects to transport them to certain areas or hosts. Unfortunately, we aren’t sure what insects Ceraphron carinatus or Conostigmus schwarzi parasitize or what their natural histories are, making it difficult to determine where they picked up these deutonymphs or where they may transport them.

While looking through European specimens recently, I discovered another mite on the back of the head of a Conostigmus female. Dr. O’Connor identified it as another astigmatid deutonymph, possibly belonging to the family Hemisarcoptidae or Winterschmidtiidae. According to Dr. O’Connor, some hemisarcoptids and winterschmidtiids are generalist phoretics.

Unfortunately, there is as little known about these mites as the ceraphronoids they were found on, but progress is being made on their taxonomy. “I found a lot of hemisarcoptid deutonymphs on parasitic Hymenoptera some years ago in northern Michigan,” says Dr. O’Connor. “All were undescribed at the time, but I did get two new genera described.”

Conostigmus sp. female from Europe, with an astigmatid mite attached to the back of the head. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

Special thanks to Dr. Mike Skvarla and Dr. Barry O’Connor for their help!


1 Mikó I, Masner L, Johannes E, Yoder MJ, Deans AR (2013) Male terminalia of Ceraphronoidea: morphological diversity in an otherwise monotonous taxon. Insect Systematics & Evolution 44(3–4): 261–347. doi: 10.1163/1876312X-04402002

2 Broad GR, Livermore L (2014) Checklist of British and Irish HymenopteraCeraphronoidea. Biodiversity Data Journal 2: e1167. doi: 10.3897/BDJ.2.e1167

3 Trietsch C, Deans AR, Mikó I (2015) Redescription of Conostigmus albovarius Dodd, 1915 (Hymenoptera, Megaspilidae), a metallic ceraphronoid, with the first description of males. Journal of Hymenoptera Research 46: 137-150.

4 Schaffner JV (1959) Microlepidoptera and their parasites reared from field collections in the Northeastern United States. US Government Printing Office. doi: 10.5962/bhl.title.7899

5 Dessart P (1967) Description de Dendrocerus (Macrostigma) noumeae sp. nov. de Nouvelle Calédonie [Ceraphronoidea Megaspilidae]. Entomophaga 12(4): 343–349. doi: 10.1007/BF02376920

6 Graham MDV (1984) A new species of Conostigmus (Insecta: Hymenoptera, Ceraphronoidea) from Madeira. Bocagiana 77: 1–5.

7 Dessart P (1992) Revision d’Aphanogmus fulmeki Szelényi, 1940 (Hymenoptera, Ceraphronoidea, Ceraphronidae) avec remarques biologiques. Bulletin de l’Institute Royal des Sciences Naturelles de Belgique 62: 83–91.

8 Goulet H, Huber JT (1993) Hymenoptera of the world: an identification guide to families. Research Branch, Agriculture Canada.

9 Mikó I, Deans AR (2009) Masner, a new genus of Ceraphronidae (Hymenoptera, Ceraphronoidea) described. Advances in the Systematics of Hymenoptera.: Festschrift in honour of Lubomír Masner. ZooKeys 20: 127–153. doi: 10.3897/zookeys.20.119

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ESA Eastern Branch Meeting

Last weekend, I traveled to Annapolis, MD, to attend the 89th Annual Meeting of the Eastern Branch of the Entomological Society of America (ESA). This was my first time attending this meeting and my first time being in Annapolis, which I was surprised to learn is the location of ESA Headquarters. I never knew it was so close!

Annapolis, MD, the site of the 2018 ESA Eastern Branch Meeting. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

A central theme of the conference was scientific communication. The plenary speaker was Kim Todd, a science writer who wrote a book about the life of Maria Sibylla Merian titled “Chrysalis: Maria Sibylla Merian and the Secrets of Metamorphosis“. There was also a panel discussion with Kim Todd and three other science communicators: Mike Murillo, a news anchor and reporter in Washington, D. C.; Inglasia Schrobsdorff, producer of the  Kojo Nnamdi show on Washington’s NPR station; and David Malakoff, the Deputy News Director of AAAS. Moderated by professor and extension specialist Michael Raupp, the panel gave excellent advice on how to work with the media to communicate science effectively. One piece of advice that stayed with me was from David Malakoff, who said that the key to good science communication is “distilling complexity”.

I enjoyed a display of live odonate larvae at “It’s a Bug’s World”, an annual outreach exhibition hosted by the ESA and held in conjunction with the Eastern Branch Meeting. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

I saw a talk by fellow Penn State PhD student Shelby Kilpatrick, titled “A case study on updating checklists: The bees (Hymenoptera: Apoidea: Anthophila) of Pennsylvania, USA”. To document the diversity of native bee communities and create a  checklist of all species found in Pennsylvania, Kilpatrick reached out to several insect collections for specimen records, including the Frost! From her presentation, it was clear that the collection at the Frost Museum has contributed a great deal to helping understand how many bee species are present in Centre County, PA.

This figure shows the number of bee species reported in different counties across Pennsylvania, with darker shades representing higher numbers of species present. The 5 counties with the highest number of bee species (100+) recorded are those with major insect collections within them or close by. This figure was used in a presentation at the 2018 ESA Eastern Branch Meeting by Shelby Kilpatrick, PhD student and member of the López-Uribe & Hines Labs at Penn State (CC BY 2.0). Click for source. This research is part of a larger project updating the checklist of bees in Pennsylvania; more available here.


Kilpatrick, S.K., J. Gibbs, M.M. Mikulas, S. Spichiger, N. Ostiguy, D. Biddinger, and M.M. López-Uribe. 2018. Checklist of the Bees of Pennsylvania.

Kilpatrick, S.K., J. Gibbs, M.M. Mikulas, S. Spichiger, N. Ostiguy, D. Biddinger, and M.M. López-Uribe. 2018. A case study on updating checklists: The bees (Hymenoptera: Apoidea: Anthophila) of Pennsylvania, USA. 89th Annual Meeting of the Eastern Branch of the Entomological Society of America (ESA), March 17-19th, 2018, Annapolis, MD.


Edit: This post was edited on 4/3/18. Shelby Kilpatrick is a PhD student, not a PhD candidate (yet!).

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Collection assessment!

CAP logo

We are very excited to announce our participation in the 2018 Collections Assessment for Preservation (CAP) program! The orientation materials even include a press release for us to use, which is pretty helpful (and it’s where I ripped off most of the text below). We’ll post more details as the process unfolds, but here’s the gist:

CAP helps museums improve the care of their collections by providing support for a conservation assessment of the museum’s collections and buildings. The museum will work with a team of preservation professionals to identify preventive conservation priorities. The final assessment report will help the museum prioritize its collections care efforts in the coming years.

I’m supposed to insert a quote from the director, me, here regarding the Frost Entomological Museum’s goals and/or how CAP fits into our greater strategic plan. Let me just say (ahem, write) that we take conservation very seriously. Part of our mission, in fact, is to “… preserve in perpetuity the collections of the Department of Entomology at Penn State and its partners”. Our NSF CSBR grant helped us take a GIANT leap towards that goal, with new storage units, as did my participation in the ECN’s collection management workshop in 2016. The latter experience really encouraged me to finalize our collections management policy document and our collections procedures (see “policies” link in menu above). More below from the press release:

“Simply by applying for the CAP program, the Frost Entomological Museum has shown a commitment to preserving cultural heritage,” said Tiffani Emig, Programs Director for FAIC. [And presumably natural history; we don’t have much in the way of “cultural” objects –ARD]

The CAP program is administered by FAIC through a cooperative agreement with the Institute of Museum and Library Services, a federal grant making agency that supports museums and libraries.

About FAIC

FAIC, the Foundation of the American Institute for Conservation of Historic & Artistic Works, supports conservation education, research, and outreach activities that increase understanding of our global cultural heritage. Learn more about FAIC at 

About IMLS

The Institute of Museum and Library Services is the primary source of federal support for the nation’s 123,000 libraries and approximately 35,000 museums. Our mission is to inspire libraries and museums to advance innovation, lifelong learning, and cultural and civic engagement. Our grant making, policy development, and research help libraries and museums deliver valuable services that make it possible for communities and individuals to thrive. To learn more, visit and follow us on Facebook, Twitter and Instagram .

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Cleptes purpuratus – a new species and subfamily for the Frost collection

After I’ve spent a few days in front of a computer working on presentations or papers, I need to see a real insect. That can be difficult during the winter when few insects are active outdoors in Pennsylvania, so the next best thing is looking through samples that I or others in the lab have collected in years past. There’s also something relaxing about sorting through samples, a zen-like quality that can come over you as your poke around and look at all of the different insects that can help reset your psyche after monotonous or stressful work.

With this in mind, a few weeks ago I was looking through yellow pan traps that Carolyn had collected in Wasatch County, Utah in July 2016. I pulled out some ants and other groups that are of interest to me that aren’t well represnted in the Frost Museum collection, at least in terms of species from the Western US. Then I saw it, a strange-looking wasp that I couldn’t immediately identify to family. Considering that’s that Penn State pays me for (insect ID), the times I can’t identify an insect to a gross level like family are not especially common and always a time for excitement. I had some ideas, perhaps a cockroach wasp (Ampulicidae) or something similar, but would have to curate the specimen and examine it using a better microscope.

Lateral view of mystery wasp, which was eventually identified as Cleptes purpuratus.

Under higher magnification, I could tell immediately this wasn’t a cockroach wasp. The mandibles and overall look weren’t right. But I still didn’t know what it was. However, turning the specimen around and examining the wings gave a clue. The wing veination indicated the was was some kind of chrysidoid.

Cleptes purpuratus, dorsal view. Wing veins outlined in red on right.

Five of the seven extant families that comprise Chrysidoidea are present in North America: Bethylidae, Chrysididae, Dryinidae, Embolemidae, and Sclerogibbidae. Embolemidae and Sclerogibbidae are species-poor families that are rarely collected and don’t look like the mystery wasp. Dryinidae look more similar, but most females have chelate (i.e., pincer-like) foretarsi, which this specimen lacks; they also have 10-segmented antennae, while  this specimen has antennae with 13 segments.  Bethylidae can have 13-segmented antennae and are diverse in North America (~200 species), but have elongate heads and are often ant-like in appearance. They also have 6 or 7 visible abdominal segments, while this specimen only has 5.

The only family left is Chrysididae, the cuckoo wasps. The chrysidids that most people are familiar with are metallic green with coarse sculpturing and can roll into a ball due to the underside of the abdomen being concave. These chrysidids belong to the nomative subfamily, Chrysidinae.

Chrysidinae cuckoo wasp, which is the group most people are familiar with. Photo by Wasrts, licensed under CC BY-SA 4.0 via Wikimedia Commons,

However, there are two other chrysidid subfamilies, Amiseginae and Cleptinae, which are not often collected. I’d collected a species of Amiseginae in Arkansas (Amisega kahlii, which parasitizes stick insect eggs) and knew it wasn’t that subfamily, but had never seen a cleptine chrysidid before. Could it be Cleptinae?

Head of Cleptes purpuratus specimen. The sulcus (groove) down the middle is an important character that separates Cleptinae from Amiseginae.

Luckily, a few years ago I bought a copy of Bohart and Kiimsey’s (1982) “Synopsis of Chrysididae in America North of Mexico”, which has keys to the subfamilies and species of cuckoo wasps in North America, as well as distribution and biological information. Working through the keys, I found that yes, this is indeed a cleptine, specifically Cleptes purpuratus. The species is known from California, Nevada, and western Utah, so while this specimen was collected a bit east of the known range of the species, it’s within reason. They parasitize species of Neodiprion , which are sawflies that feed on pines and other conifers.

All-in-all, a really neat beast that is a new species and subfamily for the Frost collection and me personally.

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Happy 209th Birthday, Darwin!

Charles Darwin was born on February 12th, 1809. Last year, I had the pleasure of taking a class taught by Benoît Dayrat focused solely on reading and discussion Darwin’s “On the Origin of Species”, which I would like to discuss today in honor of Charles Darwin on his birthday.

Darwin is most famous for his theory of descent with modification, but he also had early ideas about kin selection, where natural selection favors behavior by individuals that may decrease their chance of survival but increase that of their kin (who share a proportion of their genes). Though he was one of the greatest scientific thinkers of the 19th century, he was limited by the scientific knowledge available to him in his day; he wasn’t aware of continental drift, and thought that all species spread by migration only.

A statue of a young Charles Darwin, which stands at Cold Spring Harbor Laboratory in NY. Photo by Nathan Siemers (CC BY-SA 2.0). Click for source.

Darwin anticipated that his book would not be well received. He thought very carefully about how to overcome this, developing his ideas and collecting data for over 23 years. In his writing, he presents both well-known facts and data from his own experiments to prove his points, but he goes much further than this.

He crafts his writing to build a convincing argument that relies on logic and reason as well as fact. He introduces his ideas very slowly, and repeats them over and over so that the audience can become accustomed to them and understand them fully. In some cases, he asks questions and then accompanies the audience along a logical trail of thought until they come to the same conclusions themselves.

Darwin anticipates the weaknesses in his theory. He presents these weaknesses as “grave difficulties” to his audience, but this is often an exaggeration; after presenting each “grave difficulty”, he then explores the issue in detail, taking it apart piece by piece and showing how the “difficulty” actually fits into his theory of descent with modification. Oftentimes, he is even able to show that the issue at hand can only be explained by descent with modification. By the end, they are hardly “grave difficulties” at all, but arguments proving his point.

An illustration of a bat from Charles Darwin’s “Zoology of the Voyage of H.M.S. Beagle, 1839–43, vol. 1, Mammalia”. Image from APS Museum (CC BY-NC 2.0). Click for source.

Darwin takes every opportunity to attack independent creation, spending a large portion of one chapter dismantling the idea that an eye is a perfect structure that could only have been created by divine means. He compares the eye to a microscope— though it may seem to work perfectly, it was not created in a single day. Instead, it was the result of many modifications to a structure over the course of several years. In another section, Darwin points out that bats are the only native mammals found on marine islands, and asks why a divine being would only create bats there and no other mammals. He says that this is clearly not the product of divine influence, but the result of migration; bats can migrate to places other mammals can’t.

Darwin thought that we should not marvel at the perfection of nature because there is no perfection in nature (he asks that if nature was perfect, then why would a bee die after stinging?). The reason there is no perfection in nature is because all organisms are a product of their history, not perfect creation.

Darwin believed that a species was just a variety that became more distinct over time. If Darwin were alive today, he would say that it is impossible to discover species because they are undiscoverable; the term “species” is arbitrary. We should not focus on what the qualities or essence of a “species” is; instead, we should wonder about its history.

An illustration from the The Boy’s Own Paper, 1892, showing several varieties of fancy pigeons. Charles Darwin bred pigeons himself, and discusses them several time in his “On the Origin of Species”. Image by seriykotik1970 (CC BY 2.0). Click for source.

The class I took on Darwin’s “On the Origin of Species” was an enlightening experience for all involved. Other students in the class were impressed by the sheer amount of experiments Darwin did and data he amassed over 23 years. Many of his experiments involved pigeons, which we joked were Darwin’s favorite, though there was one memorable experiment in which he tested if snails could travel to other ponds by clinging to the legs of waterfowl. Darwin tested this by suspending a disembodied duck leg in a fish tank full of snails.

Personally, I was impressed by his rhetoric and the eloquence of his writing. Darwin’s mastery of the English language is extraordinary, and his skill as a science communicator is something that needs to be acknowledged more. He put an incredible amount of thought into every word he wrote. A perfect example of this is in the ending: the last word of the book is “evolved”. It is the first time that this word is mentioned in the entire book, and it is the word he chose to end it on.

Special thanks to Benoît Dayrat for teaching me about Charles Darwin!

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