The Crypt-Keeper Wasp: An Interesting Parasite and Its Effects

Updated on May 11, 2020
AliciaC profile image

Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about living things.

A crypt-keeper wasp
A crypt-keeper wasp | Source

An Interesting Hyperparasite

The crypt-keeper wasp (Euderus set) is an interesting and attractive insect that was discovered in 2017. It’s a hyperparasite, or one whose host is also a parasite. It parasitizes an insect known as the crypt gall wasp (Bassettia pallida). The crypt-keeper wasp controls the crypt gall wasp’s behaviour, forcing it to do the parasite’s bidding and killing it after it has served its function.

For many people, the word "wasp" probably conjures up the image of a large, black and yellow insect that is capable of giving a painful sting. Though these insects can be very annoying, they are only a small component of the wasp group. Most wasps are parasites that don't sting. Parasitic wasps are one of the largest groups of insects. Some species can be very helpful in controlling pests.

Classification of the Insects

Phylum Arthropoda

Class Insecta

Order Hymenoptera

Family Eulophidae (includes the crypt-keeper wasp)

Family Cynipidae (includes the crypt gall wasp)

Origin of the Crypt-Keeper Wasp's Name

The species name in Euderus set comes from Set, the name of the Ancient Egyptian god of evil and chaos. Set was also known as Seth. One of the stories about the god describes him trapping his brother Osiris in a crypt and then killing him. A crypt is an underground chamber that is often located under a church and used for a burial.

The crypt-keeper wasp enters the gall or "crypt" of the crypt gall wasp, where the latter insect dies from the effect of E. set's actions. The species name is apt because the sequence of events is reminiscent of the god's behaviour.

Euderus set was discovered and named by scientists at Rice University in the United States. The insect was discovered in Florida but has now been found in other states in the southeastern U.S.

Facts About Euderus set

Insects are classified in the phylum Arthropoda and the class Insecta. Wasps, bees, ants, and sawfiles belong to the order Hymenoptera within the insect class. Euderus set belongs to the family Eulophidae within the Hymenoptera order.

The crypt-keeper wasp has an attractive body with an iridescent turquoise and green sheen. It's a tiny insect whose length ranges from little over a millimetre to slightly over two millimetres. The size might explain why it wasn't discovered until 2017.

It's intriguing to think about the hidden and often energetic activities of creatures too small for us to notice or appreciate without magnification. Being small doesn't necessarily mean that a creature is insignificant. The crypt-keeper wasp might be important.

A parasite is an organism that lives in or on another organism (the host) and obtains its food from this organism. It generally doesn't kill its host. Organisms in the parasitoid category of parasitism do kill their hosts at some point, however. Euderus set is a parasitoid because it infects and eventually kills the crypt gall wasp.

An oak apple is a gall on an oak tree.
An oak apple is a gall on an oak tree. | Source

Plant Galls

Galls are areas of abnormal tissue on or near the surface of plants. Their creation is a response to the presence of insects, mites, fungi, bacteria, and viruses. Their exact cause or causes are not completely understood. The abnormal tissue may result from irritation of the area or from stimulation by the parasite. The study of plant galls is called cecidology.

Galls generally appear as swollen structures on the surface of plant parts, as shown in the photo above. They have a wide variety of appearances and are often attractive as well as interesting. They are sometimes likened to benign (stationary and non-cancerous) tumours in humans. They are usually harmless, but when they're numerous they may create a problem. The gall sometimes benefits the invader in some way, such as by providing a protected area for an insect's eggs to develop.

Although the crypt gall wasp belongs to a family that often triggers the production of noticeable galls on plant surfaces, it produces atypical effects. An affected twig or branch may look a little swollen overall, but it has no external galls. Instead, the twig or branch contains small holes. Each leads to a compartment known as a crypt (or a gall) where the insect's egg develops. In a heavy infestation, a branch may have many holes and crypts. The crypt can be seen in the video above.

Scientists have recently discovered that the crypt-keeper wasp can also infect other species of gall wasps, including ones that create typical galls on oak trees. These galls are sometimes known as oak apples.

Quercus geminata or the sand live oak
Quercus geminata or the sand live oak | Source

Facts About Bassettia pallida

The crypt gall wasp is orange-brown in colour. Like its crypt, it can be seen in the video above. It lives in the southeastern United States and is a parasite of sand live oak trees, or Quercus geminata. It sometimes infects the southern live oak, or Quercus virginiana. The first tree is evergreen and is found on the coast of the southeastern United States. It grows in sandy substrates. The southern live oak is another evergreen tree that grows in the same region but is usually found in a different habitat. It grows in grasslands and forests.

The female wasp deposits her eggs in young stems. The eggs hatch and turn into larvae inside the crypts that form. Eventually pupae are produced followed by the production of the adult insects. The new adults chew a hole in the bark and escape. The immature crypt gall wasps obtain nutrients from the tree and are therefore categorized as parasites.

Oak Alley Plantation in Lousiana contains a walk bordered by Quercus virginiana, or southern live oaks
Oak Alley Plantation in Lousiana contains a walk bordered by Quercus virginiana, or southern live oaks | Source

The Relationship Between the Two Insects

A female crypt-keeper wasp (E. set) deposits her eggs in a compartment occupied by a crypt gall wasp (B. pallida). The relationship that develops between the insects is sometimes known as hypermanipulation because one parasite affects the behaviour of another.

A parasitized B. pallida chews an opening to the outside world in the wall of the crypt, as it would do if it was going to escape. The hole is too small, however. When the gall wasp tries to travel through it, its head becomes stuck in the hole and blocks the opening. A crypt-keeper wasp feeds on its body and eventually creates a tunnel in its head so that it can escape. The parasitoid somehow controls the ability of B. pallida to chew a hole of the correct size. E. set can escape from the hole but B. pallida can't.

The parasitoid appears to affect the adult stage of B. pallida. Both the larva and the pupa of the parasitoid are able to infect the adult crypt gall wasp. Researchers have discovered E. set individuals half inside and half outside their host's body. The parasitoid eats the gall wasp from the inside out, leaving bits of the exoskeleton (the outer covering) in the crypt.

The image below shows a male Biorhiza pallida, a relative of the crypt gall wasp. In real life, the wings are folded over the body. Like the crypt-keeper wasp, the insect can be seen with the unaided eye but is tiny.

A cynipid wasp known as Biorhiza pallida
A cynipid wasp known as Biorhiza pallida | Source

Control of the Host

The relationship describe above may sound more like predation than parasitism and the gall wasp may sound more like prey than a parasite host. E. set is categorized as a parasite and B. pallida as its host, however, because E. set appears to manipulate the host's behaviour and doesn't kill it immediately. This manipulation causes the host to behave in a way that benefits the parasite.

An interesting fact has been discovered experimentally. E. set is three times less likely to be able to create a successful emergence hole when it's left to its own devices than when B. pallida creates the hole. It seems to be beneficial to allow B. pallida to create the hole before killing it.

Some researchers suspect that the crypt-keeper wasp turns the crypt gall wasp into a "zombie", perhaps by means of a specific chemical or mixture of chemicals. Chemical control has been found in some other parasites. So far, however, none has been found in the crypt gall wasp. Reports about one insect "brainwashing" the other or about E. set being able to use "mind control" to influence B. pallida are premature and may not be accurate.

Another possibility is that a specific behaviour on the part of the host or a specific condition in the crypt may trigger E. set to attack its host at the right time. The timing of the attack may enable the host to create a large enough hole for E. set's exit while ensuring that the host is too weak to finish the task and escape itself. The precise control of the exit hole size is impressive, whatever factor or factors are responsible.

Further research is needed in order to discover how the host is controlled and to learn more about the sequence of events in the crypt.

Studying the Crypt-Keeper Wasp

Since the crypt-keeper wasp has been discovered very recently, there is probably a lot more that can be learned about it. The new report about its ability to parasitize additional hosts besides the crypt gall wasp is an example of how little we know about the insect.

E. set is interesting biologically and may be important in other ways besides simply increasing our knowledge of parasitic wasps. Its effects on other insects may tell us something about their activity or even help to keep them under control. This may be very helpful if the other insects have benefits or disadvantages in our lives. The crypt-keeper wasp may be more significant than we realize.


  • Discovery of the crypt-keeper wasp from Rice University
  • Description of a new species of Euderus from ZooKeys and Pensoft
  • A parasitoid manipulates the behaviour of a parasite from The Royal Society Publishing and the US National Library of Medicine
  • The story of Set and Osiris (PFD document) from the University of Texas
  • Information about plant galls from Trees for Life (a registered Scottish charity)
  • The crypt gall wasp and its manipulation from New Scientist
  • The crypt-keeper wasp can control seven additional species from New Scientist

© 2019 Linda Crampton


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    • AliciaC profile imageAUTHOR

      Linda Crampton 

      5 months ago from British Columbia, Canada

      Thank you very much, Peggy. I appreciate your kindness.

    • Peggy W profile image

      Peggy Woods 

      5 months ago from Houston, Texas

      Another interesting article! I have never spotted the very colorful crypt keeper wasp in our area, and yet, we have many live oak trees, and I have noticed galls. Your articles are always so informative!

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      7 months ago from British Columbia, Canada

      Thanks for the visit and the comment, Eman.

    • Emmy ali profile image

      Eman Abdallah Kamel 

      7 months ago from Egypt

      It is the first time that I have read about The crypt-keeper wasp. Thank you, Linda, for this informative and educational article.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      8 months ago from British Columbia, Canada

      Thank you very much for such a kind comment, Mel. I find nature fascinating and appreciate its beauty, but I agree that it can also be cruel. I think some people like to avoid thinking about the unpleasant side of nature.

    • Mel Carriere profile image

      Mel Carriere 

      8 months ago from San Diego California

      You are always coming up with these articles on a topic that hardly anybody knows about, but is acutely interesting. I read this with the utmost fascination, and horror. Nature is a cruel, cruel place. Splendid work!

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      8 months ago from British Columbia, Canada

      Hi, Patricia. I appreciate your comment. I admire wasps, too, but I'm careful when I observe them. Thank you very much for the visit and for the angels!

    • pstraubie48 profile image

      Patricia Scott 

      8 months ago from North Central Florida

      This is totally fascinating and at the same time horrifying. What a complex relationship is formed. It is simply quite a lot to imagine that these small creatures can execute their plan as they do. And how beautiful that crypt keeper is. I am no fan of any wasp as I am very allergic. I can admire them from a distance Thank you for filling in some holes in my gray matter. Angels are headed your way this afternoon. ps

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      9 months ago from British Columbia, Canada

      Hi, Denise. The relationship is certainly interesting! Blessings to you, too.

    • PAINTDRIPS profile image

      Denise McGill 

      9 months ago from Fresno CA

      Fascinating and a bit scary: a zombie wasp. Wow. I didn't know about this. Thanks for the science info.



    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Thank you very much, Shaloo.

    • swalia profile image

      Shaloo Walia 

      10 months ago from India

      I have learnt more about Flora and fauna through your hubs than I did in my biology classes. Keep up the good work!

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Hi, Dora. I appreciate your visit and comment. I think that nature is always interesting to investigate.

    • MsDora profile image

      Dora Weithers 

      10 months ago from The Caribbean

      Everything has a purpose, they say, so I accept that these wasps have some significance. Thanks for always bring us information we would not otherwise seek out, on these phenomenal creatures.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Thanks for the visit, Nithya. Nature can certainly be very surprising.

    • Vellur profile image

      Nithya Venkat 

      10 months ago from Dubai

      Nature has many surprises in store waiting to be discovered. Thank you for sharing an interesting and informative article about the crypt-keeper wasp.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Hi, Heidi. The fact that we are still discovering new species is amazing and exciting. Nature is impressive!

    • heidithorne profile image

      Heidi Thorne 

      10 months ago from Chicago Area

      Isn't it amazing that we're still discovering new species of plants and animals all the time! So fascinating. Thanks for introducing us to another new entry in our biological world!

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Hi, Nell. Yes, it seems that many aspects of nature are still unknown. I think that parasitic wasps are interesting animals.

    • Nell Rose profile image

      Nell Rose 

      10 months ago from England

      They say nature is fascinating, and sometimes it will get a bit creepy. I think I read at the top that it was only discovered in 2017? Just goes to show what is out there that we know nothing about. How fascinating, and yes rather horrific!

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Hi, Flourish. It is a strange situation, It will be interesting to see what else scientists discover about the relationship between the wasps.

    • FlourishAnyway profile image


      10 months ago from USA

      This could be straight out of sci fi. How strange but true. I've seen those galls and wondered what they were.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Hi, John. I agree—the wasps are well named and their relationship is certainly interesting! Thank you for the comment.

    • Jodah profile image

      John Hansen 

      10 months ago from Queensland Australia

      Wow, Linda, I knew a lot of wasps were parasitic but had never read about this particular wasp. How well named it and it’s unfortunate host are. I found this very interesting, especially how it could exercise control over the host to create the perfect size for itself to escape.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Thank you for the visit and the comment, RoadMonkey.

    • RoadMonkey profile image


      10 months ago

      Very interesting, thanks. I had not known about hyperparasites before.

    • Kailua-KonaGirl profile image


      10 months ago from New York

      Cool Beans! Thanks so much.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      Hi, KonaGirl. Thanks for the visit. Some wasps can definitely sting! These include the familiar wasps that most people notice. Many more wasp species exist than these familiar ones, though. As I say, most wasps are parasites and can't sting. I'll add a few more words to the article about this topic.

      I appreciate your suggestion for my next article!

    • Kailua-KonaGirl profile image


      10 months ago from New York

      A really interesting article. A couple of things caught my eye, other than the facts about the E set, in the second paragraph of the article.

      1) I am highly allergic to ALL insect stings (yupper. . . even skeeters) which makes me avoid yellow jackets and wasps like the plague. You stated that wasps don't sting humans. Is this really true? I no longer need to worry about wasp stings? Around here we have huge black ground wasps that are really scary looking and freak me out because of my allergies.

      2) I am now really interested in the wasps that may be beneficial to killing other insects in a vegetable garden because of another fact you listed, "Some species can be very helpful in controlling pests." I am going to research this, however, it would be an idea for your next article. Hint, hint.

    • AliciaC profile imageAUTHOR

      Linda Crampton 

      10 months ago from British Columbia, Canada

      That's an interesting description of a insect, Bill! Thanks for the visit.

    • billybuc profile image

      Bill Holland 

      10 months ago from Olympia, WA

      I get along fine with wasps. I leave them alone and they do the same for me...but in the "bee" world, they are the scariest looking. :) They always remind me of a flying battleship for whatever reason. :)


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