Ambrosia symbiosis literature

The ambrosia symbiosis is a reciprocal mutualism in which ambrosia beetles obligately farm ambrosia fungi in wood. This page will eventually include some basic information about my two favorite parts of the system, ambrosia fungi and mycangia. For now, there is just a list of public domain historical literature for download below.

Historical Literature

What is here?

Below is a collection of selected public domain (pre-1926) historical literature about the ambrosia symbiosis. My hope is that this makes these works more known and accessible to the broader ambrosia symbiosis research community.

Click the arrow to the right of each title to access download links and more details about each piece of literature. Notes/opinions and rough English translations are my own, so use them with caution!

What about after 1926?

See the "other important literature" section below.

Literature List

1836: Schmidberger, J. Naturgeschichte des Apfel Borkenkäfers, Apate dispar.
Translation: Natural history of the apple bark beetle, Apate dispar.
Beiträge zur Obstbaumzucht und zur Naturgeschichte der den Obstbäumen schädlichen Insekten 4:213–230.
Highlights: First discovery of ambrosia symbiosis, introduction of term "ambrosia".
Expand for download link and details.

Files: Schmidberger_1836.pdf
Language: German
Notes: Here, the Austrian monk Schmidberger was the first to report on the white substance that the study organism, Anisandrus dispar, seemed to feed on exclusively. Schmidberger calls the white substance "ambrosia" and this is how we continue to refer to it today. Schmidberger had no idea it was fungus. Here is a Wikipedia site (in German) about Schmidberger.

1844: Hartig, T. Ambrosia des Bostrichus dispar.
Translation: Ambrosia of Bostrichus dispar.
Allgemeine Forst- und Jagdzeitung 13:73–74.
Highlights: First recognition of "ambrosia" as fungi.
Expand for download link and details.

Files: Hartig_1844.pdf; and an imperfect English translation of the most important paragraph by myself.
Language: German
Notes: Hartig examines the ambrosia of Anisandrus dispar and reports, for the first time, that it is a fungus. He describes the fungus as Monilia candida, but we now know this fungus as Ambrosiella hartigii, named after Hartig. Hartig was mistaken in thinking that the fungus spontaneously appeared in wood from the tree's sap.

1860: Wallace, A.R. Note on the habits of Scolytidae and Bostrichidae.
Transactions of the Entomological Society London 5:218220.
Highlights: Proposes that Scolytinae generally attack only trees that are weakened or dead and are often wrongly blamed for causing tree death.
Expand for download link and details.

File: Wallace_1860.pdf
Language: English
Notes: This paper isn't directly related to ambrosia symbiosis, but the recognition that scolytines don't attack trees to kill them is an important step towards discovering why they attack trees (for ambrosia beetles and some bark beetles, to farm fungi). This paper also includes some amusingly poetic lines such as "With a remarkable deficiency both of instinct and reason, the little creatures had dug their own graves, and were all glued fast by the hardening of the milky sap...(eventually) hundreds were seems evident, therefore, that this tree could not have been the proper food of this species, or the right place to deposit its eggs.".

1872a: Hartig, T. Der Fichten-Splintkäfer Bostrichus (Xyloterus) lineatus.
Translation: The spruce bark beetle Bostrichus (Xyloterus) lineatus.
Allgemeine Forst- und Jagdzeitung 48:181–183.
1872b: Hartig, T. Der Buchen-Splintkäfer Bostrichus (Xyloterus) domesticus.
Translation: The beech bark beetle Bostrichus (Xyloterus) domesticus.
Allgemeine Forst- und Jagdzeitung 48:183–184.
Highlights: Proclaimed that ambrosia fungi were the main part of ambrosia beetle diets.
Expand for download link and details.

File: Hartig_1872a_and_1872b.pdf
Language: German
Notes: In these two articles in the same volume, Hartig treats Trypodendron lineatum and Trypodendron domesticum and their fungi (we now now both beetles have Phialophoropsis ambrosia fungi). Hartig notes the similarity to the ambrosia fungus of Anisandrus dispar that he studied three decades previous, and supposes that the fungi are the main food for both larvae and adult beetles.

1873: Beling, T. Beitrag zue Naturgeschichte des Bostrychus lineatus und Bostrychus domesticus.
Translation: Contribution to the natural history of Bostrychus lineatus and Bostrychus domesticus.
Tharander forstliches Jahrbuch 33:17–43.
1877: Beling, T. Die Ernährungsweise der Larve des Trypodendron.
Translation: The diet of the larva of Trypodendron.
Tharander forstliches Jahrbuch 37:140–143.
Highlights: Beling argues against Hartig, taking the incorrect stance that Trypodendron beetles and larvae mainly eat wood and only occasionally eat fungi that happen to be around them.
Expand for download link and details.

Files: Beling_1873.pdf and Beling_1877.pdf
Language: German
Notes: Beling argues, incorrectly, that Trypodendron larvae must mainly eat wood, not fungi. I have not translated through either paper thoroughly, and this concise summary is as cited in Francke-Grosmann 1967. There might be other insights hidden in these old papers.

1895: Goethe/Göthe, R. Der ungleiche Borkenkäfer, Xyleborus (Bostrichus) dispar Faber.
Translation: The unusual bark beetle Xyleborus (Bostrichus) dispar Faber.
In: R. Goethe, ed., Bericht der Königliche Lehranstalt für Obs. Wein- und Gartenbau an Geisenheim am Rhein für das Etatsjahr 1894/1895, pp. 25–26.
Highlights: First statement that ambrosia beetles must introduce their fungi to wood; first illustration of an ambrosia fungus.
Expand for download link and details.

Files: Goethe_1895.pdf; and an imperfect English translation by myself.
Language: German
Notes: Goethe briefly treats Anisandrus dispar, including an illustration of its ambrosia fungus Ambrosiella hartigii. This appears to be the first illustration of an ambrosia fungus. Goethe makes a few other notable remarks, including (translations mine) that "growth (of the fungus) serves quite undoubtedly as food to the beetles" and "It may be assumed that the fungal spores are most likely brought into the tunnels by the beetle."

1896: Smith, E.F.  Vegetable Physiology.
The American Naturalist 30:318–323.
Highlights: Gives an interesting perspective of the state of ambrosia research pre-1897 as well as the development of Hubbard's soon-to-come work.
Expand for download link and details.

Files: I can't share my file due to JSTOR's Terms & Conditions of Use, but a stable link to the document that you can download yourself is here:
Relevance: #general
Language: English
Notes: The whole piece is a general review on Vegetable Physiology. The discussion on Ambrosia happens to be the very first topic.

1895: Hubbard, H.G. Communication.
Proceedings of the Entomological Society of Washington, Washington, D.C. 3:291–292.
1896: Hubbard, H.G. Communication.
Proceedings of the Entomological Society of Washington, Washington, D.C. 3:318.
Highlights: Some insight into H.G. Hubbard's work leading up to his 1897 review.
Expand for download link and details.

Files: Hubbard_1895.pdf and Hubbard_1896.pdf
Language: English
Notes: These are two brief, untitled communications from H.G. Hubbard that were recorded as part of the Proceedings of the Entomological Society of Washington, D.C. in 1895 and 1896.

The 1895 piece is interesting because, besides sharing some basic descriptions of ambrosia, Hubbard shares the theory that ambrosia fungi are a "ferment set up in the sap of the tree and augmented by the presence of animals". This follows the spontaneous generation theory of Hartig before him, but is very different from the conviction Hubbard had two years later that ambrosia beetles must introduce the fungi themselves. The 1895 piece goes on to describe Hubbard's discussion with the members present as "taking the form of questions and more or less unsatisfactory suggestions as to the nature of the ambrosia." Did this "unsatisfactory" discussion push Hubbard to think differently?

The 1896 piece is a very short, and apparently first, description of galleries of Xyleborus xylographus. He describes large numbers of mites/mite eggs in the galleries. Hubbard supposes that Scolytidae have a "very high order of intelligence". This piece is sometimes cited, including shortly after it was published, with the made-up title "The brood cell of Xyleborus xylographus", usually in parentheses.

1897a: Hubbard, H.G. Ambrosia beetles.
Yearbook of the United States Department of Agriculture, 1896, pp. 421–430.
1897b: Hubbard, H.G. The ambrosia beetles of the United States.
Bulletin of the U.S. Department of Agriculture Division of Entomology, new series, 7:9–30.
Highlights: A foundational review on the ambrosia symbiosis, including the introduction of the term "ambrosia beetle" and multiple foundational concepts for the symbiosis (expand to see full list).
Expand for download link and details.

File: Hubbard_1897_TheAmbrosiaBeetlesoftheUnitedStates.pdf
File: Hubbard_1897_AmbrosiaBeetles.pdf
Language: English
Notes: Hartig published both of these very similar papers in the same year. The longer (22 pages) "Ambrosia beetles of the United States" is a foundational review for the ambrosia symbiosis, including: 

(1) The introduction and definition of the term "ambrosia beetle".
(2) Detailed illustrations of beetles, galleries, and ambrosia fungi of species of Platypus, Corthylus, Xyleborus, Xylosandrus, Monarthrum, and Trypodendron.
(3) Besides Goethe, the first illustrationsambrosia fungi, including the first illustrations of (what we  now know as) Raffaelea (multiple species), Meredithiella  (M. norrisii), and Phialophoropsis (P. hubbardii).
(4) The first recognition that different ambrosia beetles have different ambrosia fungi.
(5) The first recognition that ambrosia fungi probably have special adaptations to be good food.
(6) Further development of Göthe's idea that the beetles introduce the fungi actively to wood.

The shorter (10 pages) "Ambrosia beetles" appears to be a condensed summary of the other work that was published in that year's USDA Yearbook.

1898: Hopkins, A.D. On the history and habits of the "wood engraver" ambrosia beetle—Xyleborus xylographus (Say), Xyleborus saxeseni (Ratz.)—with brief descriptions of different stages.
The Canadian Entomologist 30:21–29.
Highlights: Includes some interesting observations on behavior.
Expand for download link and details.

File: Hopkins_1898.pdf
Language: English
Notes: Hopkins makes some interesting observations on gallery behavior in X. saxeseni/X. xylographus (I am unsure about the correct modern-day ID here) and includes an illustration of Raffaelea (probably R. sulphurea) but otherwise defers to Hubbard on specific matters relating to fungi.

1898: Ormerod, E.A. Shot-borer beetles.
In: E.A. Ormerod, ed., Report of observations of injurious insects and common farm pests, during the year 1897, with methods of prevention and remedy pp. 74–85.
Highlights: Contemporary perspective from England, gallery and beetle illustrations, discussion on interactions with mites. Focuses on An. dispar and X. saxeseni. First note of sweet smell of ambrosia. Earliest known female author to publish on ambrosia beetles.
Expand for download link and details.

File: Ormerod_1898.pdf
Language: English
Notes: Here, Ormerod writes about Xylosandrus dispar because it caused significant problems on plum trees in English in 1897. She mostly discusses impact of galleries and unusual female/male size and ratio disparity. Includes some nice illustrations of X. dispar beetles and galleries. She describes a case where she was sent material assumed to be X. dispar attack, but she identified it instead as Xyleborinus saxeseni. Describes the obvious difference in gallery appearance between the two species, and the difference in color, texture, and aroma between the ambrosia of each. The description of sweet-smelling gallery walls in X. saxeseni appears to be the first notice of the sweet smell of ambrosia fungi. Includes some secondhand correspondence from Hopkins and excerpts with commentary from Hubbard's work from the previous year. Also discusses ambrosia beetle-related mites; wonders if the mites could be used to "steal" ambrosia and control the infestations.

Ormerod was an interesting person. Read more here.

1907–1913: Strohmeyer, H., various works.
Highlights: <In progress.>
Expand for download link and details.

Language: German
Notes: Strohmeyer had a large number of works during this period. I'm still evaluating them for relevance to the ambrosia symbiosis.

1908–1911: Neger, F., various works.
Highlights: Introduces the term "ambrosia fungi". The first basic mycology, including pure culture studies, on ambrosia fungi. Proposed that all fungi farmed by insects should be called ambrosia fungi; also includes work on ambrosia gall midge and ship-timber beetle fungi.
Expand for download link and details.

Between 1908 and 1911 Neger released a flurry of works relating to ambrosia fungi. These represent the first serious attempt at basic mycology with these fungi. These include the four works in the "Ambrosiapilze" (Ambrosia fungi) series and various others. Some brief notes on each below:

1908: "Die Pilzkulturen der Nutzholzborkenkäfer"
Translation: "Fungal cultures of timber bark beetles"
File: Not available yet.
Language: German
Notes: The first study of ambrosia fungi in pure culture. Supposes that some of the fungi that Hubbard called "monilioid" (looking like Monilia, i.e., like chains of beads) are not monilioid, because Hubbard was describing chained conidia not mycelium. As it turns out, this is true for Phialophoropsis but incorrect for Meredithiella. Neger re-affirms that the beetles must introduce the fungi to wood and that the fungi are adapted as insect food.

1908:  "Die pilzzüchtenden Bostrichiden"
Translation: "The fungus-growing bostrichids"
File: Neger_1908_DiePilzzuchtendenBostenchiden.pdf
Language: German
Notes: Neger disagrees with Hubbard that ambrosia beetles transmit ambrosia fungi "with intention". Rather, Neger supposes it must be by accident and that spores stick to beetle surfaces. Francke-Grosmann's discovery of mycangia in 1957 would show that Hubbard was correct. Neger also talks about nitrogen utilization in galleries, among other things.

1908: "Über Ambrosiakäfer"
Translation: "About ambrosia beetles"
File: Not available yet.
Language: German
Notes: Includes the first microscopic photograph of an ambrosia fungus (Ambrosiella hartigii from Anisandrus dispar) as well as illustrations of the fungus farmed by Hylecoetus dermestoides (Lymexylidae, not an ambrosia beetle). A general treatment of ambrosia beetles.

1908: "Ambrosiapilze"
Translation: "Ambrosia fungi"
Berichte der Deutschen Botanischen Gesellschaft 26a:735–754.
File: Neger_1908_Ambrosiapilze_I.pdf
Language: German
Notes: This is not about ambrosia beetle fungi at all, but the fungi of "ambrosia gall midges". I have included it here because Neger makes the interesting statement that "ambrosia" should be used collectively to refer to all fungi farmed by insects, not just ambrosia beetles, something that never took hold. Ambrosia gall midges remain understudied today. An English review of the article, from Botanical Gazette volume 49 (1910), can be found here.

1909: "Ambrosiapilze II. Die Ambrosia der Holzbohrkäfer"
Translation: "Ambrosia Fungi 2: The ambrosia of wood boring beetles"
File: Neger_1909_Ambrosiapilze_II.pdf
Language: German
Notes: Treats the fungi of various ambrosia beetles, including Trypodendron lineatum, Xyleborinus saxeseni, and Xylosandrus dispar. Illustrates what we now know to be Ambrosiella from X. dispar.
It also includes a significant non-Scolytinae contribution to fungus-farming ship timber beetles (Lymexylidae), as Neger also treats, illustrates, and names the mutualistic fungus farmed by Hylecoetus dermestoides as "Endomyces hylecoeti". This fungus was later redescribed as Ascoidea hylecoeti by Batra/Francke Grosmann and is now known as Alloascoidea hylcecoeti. Fungus-farming ship timber beetles remain understudied.
I haven't thoroughly translated through this one yet, but an English review of the article from Botanical Gazette volume 49 (1910), can be found here.

1911: "Ambrosiapilze IV. Tropische Ambrosiapilze"
Translation: "Ambrosia fungi 4: tropical ambrosia fungi"
File: Neger_1911_Ambrosiapilze_IV.pdf
Language: German
Notes: I have not translated through this one enough to extract the important bits.

1911: "Zur Übertragung des Ambrosiapilzes von Xyleborus dispar"
Translation: "On the transmission of ambrosia fungi in Xyleborus dispar"
File: Not available yet.
Language: German
Notes: Neger pontificates on the transmission of ambrosia fungus by Xylosandrus dispar. As critiqued later by Francke-Grosmann, Neger is wrong about superficial transport and fails to suppose that there might be internal organs that hold the fungus. Includes a nice illustration of what we now know as Phialophoropsis ferruginea in galleries of Trypodendron lineatum.

1914: "Zur Frage der systematischen Stellung der sog"
Translation: "On the question of the systematic position of the so-called ambrosia fungi"
File: Neger_1914.pdf
Language: German
Notes: Appears to be a discussion of the taxonomy of ambrosia fungi. I have not translated and read through this one yet, but it seems like it could be an interesting step towards later taxonomic clean-up.

Some of Neger's peripherally-related works from this period are left out. These include studies concerning tree reactions to ambrosia beetles ("Die Reaktion der Wirtpflanze auf den Angriff des Xyleborus dispar", 1909) or ambrosia galls ("Über Ambrosiagallen", 1909; "Ambrosiapilze III. Weitere Beohachtungen an Ambrosiagallen", 1910; and others).

1910: Beauverie, J. Les Champignons dits Ambrosia.
Translation: The so-called ambrosia fungi.
In: Annales des sciences naturalles, série botanique 11:31–73.
Highlights: Intricate illustrations of Ambrosiella, including the first illustration of sexual fruiting bodies (cleistothecia).
Expand for download link and details.

File: Beuverie_1910.pdf
Language: French
Notes: An in-depth treatment of Anisandrus dispar and its ambrosia fungus Ambrosiella hartigii. Includes many intricate microscopic illustrations of the ambrosia growth of A. hartigii in wood, including the first illustrations of cleistothecia, the sexual state of Ambrosiella. Sexual fruiting bodies in Ambrosiella would not be recognized until more than 100 years later by Mayers et al. 2017.

19111913, 1921: Schneider-Orelli, various works.
Highlights: <In progress.>
Expand for download link and details.

Language: German
Notes: Schneider-Orelli had a large number of works during this period. I'm still evaluating them for relevance to the ambrosia symbiosis.

1916: Berger, V.M and Cholodkovsky, N.A. Къ бiологiи и анатомiи короtЛовъ рода Scolytoplatypus Blandford (Coleoptera, Ipidae).
Translation: On some points of biology and anatomy of the genus Scolytoplatypus Blandford (Coleoptera, Ipidae).
Revue Russe d’Entomologie 16:17.
Highlights: First mycangium illustration (though incorrect theory on function).
Expand for download link and details.

File: Berger_Cholodkovsky_1916.pdf
Language: Russian
Notes: First illustration of a mycangium. The mycangium of Scolytoplatypus is illustrated in great detail from multiple angles and scales. Unfortunately, Berger and Cholodkovsky thought the organ was related to mating. It was not until 1951 that Nunberg guessed that Berger and Cholodkovsky's organ might be for spore transmission, and 1962 that W. Schedl fully characterized Scolytoplatypus mycangia and the spores carried inside them.

1917: Beeson, C.F.C. The life-history of Diapus furtivus, Sampson (Platypodidae).
Indian Forest Records 6:1–29.
Highlights: First guess that mycangia might be involved in fungal transport, though flawed (expand for details).
Expand for download link and details.

File: Beeson_1917.pdf
Relevance: #mycangia
Language: English
Notes: On page 14, in the section "Transport of the Ambrosia", Beeson remarks on the large pronotum pits (which we now know to be mycangia) of Diapus furtivus (now called Genyocerus talurae; see Beaver and Liu 2007). Beeson wonders if these pits are connected to the transport of fungi, and guesses that fungal spores might adhere to the sticky globules of oil/fat in each pit. Beeson was slightly off, as spores are actually carried inside the pits. This appears to be the first time that pronotal pits were connected to spore transport, and arguably the first hypothetical connection of mycangia to spore transport.

Note about literature:
This list is incomplete and only includes papers of special interest to me (i.e., those involving ambrosia fungi and/or mycangia). For wider literature hunting it's worth noting that in 1939 R. Kleine published a detailed list of pre-1938 bark/ambrosia beetle literature ["Gesamtliteratur der Borkenkäfer (Ipidae und Platypodidae) bis einschließlich 1938; Stettiner Entomologische Zeitung volume 100]. It's not in the public domain so is not shared here, but is worth tracking down. Although in German, it's mostly an easily readable list.

If you find a mistake or have a suggestion that can be added to the page, please email me at cgm227 (at) cornell (dot) edu or chasemayers (at) gmail (dot) com.

Other important literature

General Reviews

There is no better overview of the first 100+ years of ambrosia and bark beetle symbiosis research, and of her own significant contributions to the field, than Francke-Grosmann's foundational 1967 review chapter "Ectosymbiosis in wood-inhabiting insects" in Symbiosis Volume II (edited by S.M. Henry). Much of Francke-Grosmann's most important work was published in German, and it is summarized excellently in English in this chapter. The chapter is still relevant today and I think it should be required reading for any ambrosia researcher. You might have free access from Academic Press, but if you don't, don't pay the high prices for a .pdf or for a rebound copy of the chapter. I have seen used copies of Symbiosis Volume II (just make sure it's not Volume I) for as little as $3 on websites such as, and currently (early 2021) I see multiple copies of the two-volume set selling for less than $20.

For further information on the ambrosia symbiosis, a variety of reviews provide context through history:

For further information on ambrosia fungi, things have changed quickly recently and there has not been a recent comprehensive fungi-centric review. I would suggest to check out the summaries on my Publications page for Ceratocystidaceae species (Ambrosiella and allies).

For further information on mycangia, I humbly present our 2022 review chapter on mycangia, which is available open access through MIT press here; a summary and representative figures are given on my Publications page.

Selected ambrosia milestones not in the public domain, pre-1968

This is not an exhaustive list!

1951: Nunberg, M. Contribution to the knowledge of prothoracic glands of Scolytidae and Platypodidae (Coleoptera).
Annales Musei Zoologici Polonici 14:261–267.
Highlights: Illustrates the mycangia of Trypodendron, Diapus, Dactylipalpus, and Phloeoborus for the first time. First to connect these structures together and guess that their purpose might be to carry ambrosia fungus propagules inside them, though he wasn't able to prove this with dried specimens.

1956: Francke-Grosmann, H. Hautdrüsen als träger der pilzsymbiose bei ambrosiakäfern.
Zeitschrift für Morphologie und Ökologie der Tiere 45:275308.
Highlights: An extremely important milestone and what I consider to be the discovery of mycangia. Unaware of Nunberg's work (as she would explain in the '67 review chapter), Francke-Grosmann independently discovered mycangia in multiple different beetle species and, crucially, proved that they carried and maintained ambrosia fungus spores inside of them.
Available via Springer.
Text is in German. I have made a partial English translation of this work, available on request.

1962: Schedl, W. Ein Beitrag zur Kenntnis der Pilzübertragungsweise bei xylomycetophagen Scolytiden (Coleoptera).
Highlights: Many intricate and beautiful mycangium illustrations, including multiple first descriptions in Scolytoplatypus, Corthylus, and others. Especially deep discussion of Scolytoplatypus mycangia.
Text is in German. I have made a partial English translation of this work, specifically the Scolytoplatypus portion, available on request.

1963: Batra, L.R. Ecology of Ambrosia Fungi and Their Dissemination by Beetles.
Transactions of the Kansas Academy of Science 66:213236.
Highlights: Additional studies on ambrosia beetles and mycangium propagules. Most significantly, the introduction of the term mycangium/mycangia.
Available via JSTOR

1964: von Arx J.A. and Hennebert G.L. Deux Champignons Ambrosia.
Mycopathologia et mycologia applicata 25:309315.
Highlights: Descriptions of the genera Raffaelea and Ambrosiella, which would prove to be the prototypes for the two major ambrosia fungus groups (the Ophiostomatales and Ceratocystidaceae ambrosia fungi, respectively).
Available via Springer
Text is in French. I have made a partial English translation of this work, available on request.

1967: Batra, L.R. Ambrosia Fungi: A Taxonomic Revision, and Nutritional Studies of Some Species.
Mycologia 59:976–1017.
Highlights: An important milestone on the fungal side; a first comprehensive attempt to straighten out the taxonomy of ambrosia fungi. This work was an important foundation for all future taxonomic work in ambrosia fungi.
Available via JSTOR

1967: Francke-Grosmann, H. Ectosymbiosis in wood-inhabiting insects.
In Symbiosis Volume II (ed. S.M. Henry).
Highlights: In my opinion, the single most important work in the history of ambrosia symbiosis research. Scroll up to the "General Reviews" section to see my full thoughts and advice on obtaining a copy.
Available via Academic Press, though see discussion above on how to find physical copies of this chapter