Monday, September 5, 2022

Reading Bug Tracks on Tea Leaves

From palm-reading to watching Fox News, humans throughout the ages have sought knowledge through some decidedly irrational means. But every now and then, superstition pays off. For example, studying the pattern of coffee grounds in the bottom of one’s cup, a practice known as tasseomancy, will nearly always reveal that someone forgot to put a filter in the coffeemaker basket. And haruspicy, the study of the fresh entrails of a gutted animal, is consistently right in concluding the animal is dead.

The reading of tea leaves, a custom devised by 17th-century Europeans who got bored waiting for the Internet to be invented, has become quite popular among entomologists and other biologists in the past few years. It’s possible a few may secretly use this method to gain insight on their personal lives, but for the most part, tea leaves are now read by scientists to learn about insect behavior around the world. It turns out that for any given tea leaf that ever had a beetle bite it, scale-insect suck sap from it, or planthopper poop upon it, traces of DNA from each and every visitor stay behind.


Even after you’ve brewed a refreshing pitcher of iced tea, it’s possible to map out who else took a taste first. Recent breakthroughs in genetic sequencing allow for the detection of DNA remnants at extremely low levels. All it takes is a part of one sloughed-off arthropod cell on a leaf to identify its owner down to the species level. This is called environmental deoxyribonucleic acid, or eDNA for short. A July 20, 2022 Smithsonian article outlines how a team of scientists in Germany used eDNA to catalog more than 1,200 different species of arthropods on samples of parsley, mint, black tea, and chamomile. Before you panic, not all 1,200 critters are joining you in each cup of herbal or regular tea.


Hundreds of plant specimens were tested across four continents to get this number. On average, “only” about 200 different insects and arachnids left their genetic calling-cards in each tea bag. This is actually a good thing, as it shows that our tea isn’t being doused with pesticides. As noted in the Smithsonian article, eDNA is a powerful tool for monitoring insect populations, which are in freefall across the globe. In example, surveys done on nature preserves in Germany over the past twenty-seven years showed a 75% decline in the number of flying insects during that period. Similar findings are coming in from every continent. In addition, eDNA on tea leaves can help track the spread of invasive pests.

Brittney Rogers and Gabriel Yerdon of SLELO PRISM. SLELO PRISM website photo.


In light of this new study, other scientists hope to be able to obtain old specimens from botanical collections and museums. Comparing recent results with eDNA from plants plucked decades ago will give us a better understanding of trends in arthropod populations. Closer to home, the Ontario Ministry of Natural Resources uses eDNA sampling to check for oak wilt, a devastating pathogen of oak trees first identified in the US. As early as 2018, oak wilt was known to be just a few kilometres from Ontario along significant stretches of its border with Michigan. Not surprisingly, in 2020, oak wilt eDNA was detected in Ontario. However, the first confirmed case of oak wilt in Canada has yet to be found.

Oak leaf showing signs of wilting. Invasive Species Centre website photo.


In northern New York State, the St. Lawrence-Eastern Lake Ontario Partnership for Regional Invasive Species Management (SLELO PRISM) has been conducting eDNA surveys for invasive aquatic species in major tributaries of the St. Lawrence River. For the past several years, the Black, Oswegatchie, Grasse, and Raquette Rivers are being monitored for the presence of invasive fish such as the northern snakehead (Channa argus), a.k.a. Fishzilla. This über-predator would displace muskies and pike if it got established in the region, vacuuming up a great deal of the perch and bass along the way. Fishzilla is able to walk on land in search of new homes, meaning that it could conceivably shed DNA on tea leaves on its way to ravaging the local fishery.


Waters in the St. Lawrence River and eastern Lake Ontario near the US-Canada border are also checked for eDNA signatures left by silver and bighead carp, either of which could markedly degrade water quality. Hydrilla (Hydrilla verticillate), the most pernicious aquatic weed ever found in the US, is also on the eDNA watchlist. This invasive plant can grow as much as a foot or thirty cm per day in all directions, and chokes waterways as deep as twenty-five feet or six metres. With hydrilla, walking on water no longer requires a miracle. Too bad it makes lousy tea.


The German study can be found at


For more information on eDNA sampling by SLELO PRISM, visit


In Ontario, see


Paul Hetzler is a former Cornell Extension educator. After learning of this study, he prefers his tea well-cooked.


Photo at top: Cup of tea. Pexels photo.

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Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.You can read more of his work at or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World

35 Responses

  1. ADKresident says:

    “From palm-reading to watching Fox News, humans throughout the ages have sought knowledge through some decidedly irrational means…”

    Can’t help but add a partisan political side swipe, even on something that has absolutely nothing to do with the subject at hand. It just gets more obvious by the day~ the entwined personal biases that now seem to seep out into every little crevice of thought, even down to an article on leaves. Weird.

  2. JJ says:

    The Fox News joke is a swing and miss. It poorly fits the article subject of invasive species and eDNA tracing. What TV news are the rational ones that help NYS understand invasive species and eDNA surveys?

  3. Isidro Rodriguez says:

    I’m no big fan of politics or politicians (on either side of the equation), but the fact that this so-called “educator” actually believes that Fox News is irrational as compared to say ANY of the mainstream legacy media (MSNBC, CNN, et al.) is both frightening and a sign of how effective long-term indoctrination and propaganda has been on our society.

    • Dana says:

      Wouldn’t “legacy” media be CBS, NBC, ABC, PBS? You know – pre-24 hour news cycles. Three, 30 minute newscasts/day. Perhaps I am showing my age…

      • Dana says:

        To hitchhike on my above question, I would suggest any 24-hour broadcasting network will have some sort of bias, as it would have targeted viewers and sponsors. It becomes entertainment, not peer-corroborated news. Entertainment does not discourage or exclude comedy or fantasy. Watch these shows for fun, NOT double-checked facts!

  4. Worth Gretter says:

    The Media Bias Chart by Ad Fontes Media is a non-partisan ranking put together by reviewers of different political persuasions. Media outlets are ranked by political orientation (left vs right) and also by reliability (i.e. truthfulness).

    The chart shows that the “mainstream” media is only slightly to the left, and relatively truthful. Fox, on the other hand, is decidedly to the right, and a lot lower in reliability. But, as most of us already know, there is considerable variation between Fox media personalities and their shows.

    • ADKresident says:

      If depending on a media company’s chart is what some are now relying on as their basis of truth to discern media bias and journalistic intent, then it just reveals that people are failing to do their own research beyond what is on the surface, think for themselves and come their own conclusions by using their own noggin.

      • jj says:

        The story is about the cool abstract study: “DNA analysis (eDNA) has revolutionized the field of biomonitoring in the past years”

        The point about Adirondack invasive species, education and awareness and the modern techniques is being obscured by a bad reference to media and an opinion that does not matter to DNA analysis.

        The introduction could have talked about the flavors of ice cream and made more sense.

      • Worth Gretter says:

        Ad Fontes exists for the specific purpose of doing the lengthy, in depth research that no one individual has the time or resources to do.
        That said, a little critical thinking on the part of TV viewers would go a long way!

  5. Now former subscriber says:

    Keep your political views and mockery of others’ to yourself. The smug arrogance with which you include political cheap shots such as fox news being irrational, comes across as childish and puerile as it is.

  6. Jim S. says:

    Fascinating article,however injecting the title of a politically motivated news company seems to have distracted the political trolls from the subject of the article.

    • HR says:

      Oh right, because anyone calling out bias is a “troll” to the ones that have happily imbibed the propaganda of the establishment liberal elites.

  7. Pat Smith says:

    So much for uniting the nation, the snotty little comments do nothing to help us find common ground.

    • ADKresident says:

      Calling out the author’s biased injection to what is assumingly an article written for all informationally is NOT being a troll or “snotty”- it is just exposing the bent partisanship in AA that is now tainting everything, down to an article on leaves and should NOT be…Can’t have it both ways- insert personal prejudices and expect to find common ground and/or be called out for doing the opposite.

    • Jim S. says:

      I didn’t mean to be snotty, I just wanted to say that as soon as you inject a “news” organization into a scientific article you distract from the science and the article is suspect. I have no faith in either Fox or CNN.

  8. JohnL says:

    One would think that if Melissa wanted this article to be apolitical and just a nice article about bugs and tea in a magazine about bugs and tea, she might have ‘suggested’ to Mr Hetzler that he modify his 1st sentence by eliminating the totally unrelated (and incendiary) reference to Fox News. He (Mr Hetzler) could then have done as requested, or not. That what editors and authors do all the time. So, I’m left with the assumption that she (Melissa) is not only comfortable with, but maybe even enjoys seeing, this type of controversy in her almanack. No problem. I think most of us on this site can play it either way. Just thought I’d point that out.
    P.S. Most regulars on this site know where I stand on the Fox versus the main stream networks. No need to repeat that here.

    • From our website: The Adirondack Almanack is a public forum dedicated to promoting and discussing current events, history, arts, nature and outdoor recreation and other topics of interest to the Adirondacks and its communities

      We publish commentary and opinion pieces from voluntary contributors, as well as news updates and event notices from area organizations. Contributors include veteran local writers, historians, naturalists, and outdoor enthusiasts from around the Adirondack region. The information, views and opinions expressed by these various authors are not necessarily those of the Adirondack Almanack or its publisher, the Adirondack Explorer.

  9. Lynn Owre says:

    To the editor(s) of Adirondack Almanack

    Your reference to Fox News in article dated September 5
    Was completely unnecessary and not related to subject.
    The one result of that irrelevant comment was my decision to NOT subscribe to your publication.
    I do respect your right to your opinion

    • Just wanted to clarify, from our website:
      The Adirondack Almanack is a public forum dedicated to promoting and discussing current events, history, arts, nature and outdoor recreation and other topics of interest to the Adirondacks and its communities

      We publish commentary and opinion pieces from voluntary contributors, as well as news updates and event notices from area organizations. Contributors include veteran local writers, historians, naturalists, and outdoor enthusiasts from around the Adirondack region. The information, views and opinions expressed by these various authors are not necessarily those of the Adirondack Almanack or its publisher, the Adirondack Explorer.

  10. Dana says:

    Most huge corporations get the reputation they deserve. It doesn’t make it a political statement any more than calling out palm-reading. Oddly, the palm-readers out there don’t seem to take offense.

  11. Mike says:

    I just dont understand why there is so much effort to create hate and division by authors and editors today.

  12. Isidro Rodriguez says:

    Thanks, Melissa. I’ll make sure to throw in some partisan shade in my upcoming piece on deer flies.

  13. louis curth says:

    Paul Hetzler has offered readers a deeper look at bugs and tea leaves. To my surprise I discovered that his treatise has elicited 28 comments piling-on in response to an offhand dig at Fox News. Then I compared this to Tim Rowland*s very upsetting 9/5 Explorer article About Adirondack children who are falling through the cracks and urgently need our help. Guess how many comments in response? Answer – 2.

    My fellow Adirondackers, can’t we do better than just taking pot shots at each other? Isn’t there enough of that on our dismal social media sites? We don’t have to be so thin-skinned, over everything we don’t agree with. Let Melissa do her job and ride herd on anything beyond the pale.

    There is a world of hurt out there that all of us need to gather facts about and learn what we can do to try to help people in need – especially our children. Let’s try to be part of the solution rather than just adding more invective…

    • ADKresident says:

      In light of the subject at hand, of course, I would assume 99% of ADKers consider a child’s well being as far more important than digs by partisan writers. To be fair to all, I would also assume most, including myself, did not even see, let alone read the article you are pointing out.

      Also, most of us are simply getting pretty fed up with the political climate and do not subscribe to this Community Forum to read partisan jabs in subjects that have NOTHING to do with policy and/or elected officials. Wouldn’t you agree that it was unnecessary to include one’s personal biases in an article on leaves? Where is the unifying intent in that? You can be certain, if it were the other way around, there’d be no suggestion to ignore and carry on. (Just the mention of Elise Stefanik stirs up hatred that I have not witnessed in my lifetime with zero accountability, and I’m no millennial 🙂

      Therefore, I am unapologetic for calling it out which does not lessen any concern for the well-being of our children for having done so. I can maintain 2 varying thoughts at the same time…..

      Please, Louis, may I suggest calling out the one(s) responsible who planted the divisive seed, not those who responded in confrontation to what grew from it?

      Have a great day!

      • jj says:

        Good response! The introduction was deliberaly an attempt to be cute, but is plainly inflammatory. The introduction was irrelevant to the subject. The introduction should have been edited.

    • Pat Smith says:

      Mr Curth, my parents taught me that if you can’t say something nice, don’t say anything at all. Apparently Mr Hetzlers parents didn’t instill the same lesson in him.

  14. louis curth says:

    A peak at Tim Rowland’s Explorer article “Finding Ways to Break a Troubling Cycle” shows interest is still at the same 2 comments. I don’t see much there that supports ADKresident’s assumption that 99% of us care about what is happening to our children or, for that matter, would share their ideas about how to build a better system that works for north country people in need – especially the children. If that is true them shame on us all. Paul Hetzler’s comment is pretty small potatoes compared to that.

    If you wonder what my opinion is, I believe that such help will only come if we hold our elected officials accountable and demand that they stop lying to us and enriching themselves, and start working together to make our two party system work for the good of ALL of us. I left the Republican Party after more than half a century because I feel betrayed by Trump, Stefanik and our cowardly north country elected officials who still refuse to speak out and denounce the violent January 6, 2021 insurrection at the Capitol. They have lost my support and my vote.

    More importantly, this forum could be a place for us to share our ideas about how to solve our problems and restore the feeling that we are all part of. one north country community despite our differences. It is also a place that welcomes would-be authors to try our hands writing about our interests and sharing the result for others to read. I suggest we try to view this as a place of refuge in our divisive world and be glad we have it.

  15. Bill Ott says:

    A perfect place to have a private liaison with my secret sweetheart.

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