Roberta the Hairworm


By Kathy Mechling, M.D., SFI Board President

We were peering into the old horse trough to see how the tadpoles were progressing.  We saw no tads, they had probably metamorphosed and jumped out, but there was a lovely sinuous worm.  She was very thin, like spaghettini, tan colored; about 8 inches long with no obvious markings –no stripes/spots/head/tail/fin –no nothing.  She was not a familiar human pathogen, but she was familiar.

An internet search soon led past whip, flat, tape and round worms, to the lovely horse hair worms.  Turns out they are parasitic grasshoppers only.  I learned the males and females mate in big clusters (Gordian knots) in creeks or streams.  The fertilized eggs later hatch as larvae who sink to the muddy bottom since they can’t swim or float.  There, a hairworm larva “enters” the larva of an insect such as a mosquito, mayfly or midge.  Weeks or months later when that insect larva metamorphoses, it flies away carrying the hairworm cyst back to dry land.  From there, if lucky, it will be eaten by an omnivorous grasshopper.  Inside the grasshopper the hairworm cyst carefully devours most of the grasshopper guts, leaving only the jumping muscles, the heart and the brain.  When the hairworm is ready to hatch, it turns the grasshopper into its zombie and commands it to march toward water, then the final command is to jump into the water where the adult hairworm then crawls out the grasshopper’s rear.

I could not have made this up.

The internet search also turned up the Hairworm Biodiversity Project in Albuquerque.    Hot diggity!  They are recruiting “Citizen Scientists” to submit hairworms from around the world.  I quickly emailed them about my find, and Dr. Ben Hanelt wrote back that he didn’t have any critters from Oregon.  Game on.  I would encourage you to google the project.  Their logo is one of the best I have ever seen.

The horse trough hairworm was found at the Robert Whittaker house, which was named after the Ecologist who explored the Kalmiopsis wilderness in the ‘50s.  Roberta seemed to be a good name for her.  As a side note, Whittaker formulated his theories of ecosystems from data collected in the Kalmiopsis, taking careful measurements of plants and the physical characteristics of their immediate environments at his research sites.  Some brilliant scientists {1} recently revisited these same sites and documented changes in those plant communities.  Because the only significant change in the environment over the last 57 years is an increase in temperatures there of about 2 degrees, they have documented changes in ecosystems that are probably due to climate change.  Whittaker knew nothing of climate change, but his work is helping with the study of plant and animal survival and adaptation in this time of rapid environmental change..

Dr. Hanelt instructed me to put Roberta in a plastic container with clean water and then put her in my refrigerator until I could mail her, reassuring me she is not a human pathogen.  I recycled a Party Peanuts jar.  As you can see, she seemed happy there.

Monday morning we repackaged her into a Ziploc bag sealed in another bag, then into a little mailing box.  With her bags packed, she was off to warm, sunny Albuquerque.

Two days later Dr. Hanelt emailed me that my  hairworm had arrived alive and well, and that the species Gordius robustus had not been documented in Oregon before.  However, alas, he informed me that my hairworm was Robert, not Roberta.

It is such a beautiful world.



{1} Damschen, Ellen I, Susan Harrison and James B Grace.  Climate change effects on an endemic-rich edaphic flora: resurverying Roert H. Whittaker’s Siskiyou sites (Oregon, USA)  Ecology 91(12), 2010, pp3609-3619

Hairworm Biodiversity Survey:

Ben Hanelt, PhD, is a Research Assistant Professor at the Center for Evolutionary and Theoretical Immunology in the Department of Biology at the University of New Mexico

7 thoughts on “Roberta the Hairworm”

  1. So Donald Schreiweis didn’t teach you about Gordian knot worms at Gonzaga? I discussed them in my Introductory Zoology class there, maybe because I’d grown up around stock tanks teeming with horsehair worms in the Willamette Valley.

    What a great blog.

    See you at the Stupid Bowel Party.

    Dan Guthrie

  2. I was quite surprised to read about your discovery of a horsehair worm in tonight’s paper. The “wire worm”, as we also used to call it, was one of my favorite things to “hunt” for when I would explore the spring time streams and rivulets on the farm where I grew up in Hugo. As a child/youth, I would joyfully search for the horsehair worms every year, “collect” them to observe for a short while as they wiggled and coiled and twisted, and then return them to their homes to carry on with their seemingly pointless journeys. I never had a thought about their life cycle, nor did I care at the time. But they have been one of my favorite things to hunt for in all of my 63 years. In recent years, I actually did some research on them as I wanted to share my fascination with my grandsons when they visited. I had no idea they’d never been documented in Oregon, as they’ve been here forever. Back in the day, we had an abundance of grasshoppers, so that likely explains why we also had an abundance of horsehair worms. However, they are much less prevalent now and much harder to find. We did find a couple last spring, after hunting intently, in the very same wet-weather streams I used to search in as a child. They do not like fast water; only gently moving water or water like that in which you found “Robert”. I would love to know how they determine male/female!!!! In any case, it’s nice to know others find them fascinating; God showed a sense of humor when He created that one!

  3. Hi Kathy- thanks for the info. Ever since I came to this area about 25 years ago I periodically find them in the course of my research in both the Klamath and Rogue Basins.
    Jacob Kann, Ph.D.
    Aquatic Ecosystem Sciences, LLC
    295 East Main St., Suite 7
    Ashland, OR 97520

  4. I found some today when I was cleaning out an over grown pond on my property. Blackberries are so invasive. Anyways, I noticed these little strings moving in the water and it honestly freaked me out. I’m glad to hear they are not harmful, I was about to drop some chlorine tablets into the water to kill them off.


Leave a Comment