<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=915327909015523&amp;ev=PageView&amp;noscript=1" target="_blank"> Skip to main content
You are the owner of this article.
You have permission to edit this article.

Readers want to know: Wait, what are those dancing horse-like hairs moving in the water?

Also, readers comment on their own experiences with Asian jumping worms

Horsehair worm in hand

Horsehair worms, named for their similar look of horse hair moving in water, are harmless to most animals. 

Q: I have been meaning to write to you since early August [about] a small trough I keep out for animals to drink from when water might be in need. I don’t change it often, and when I do, I just tip it over and refill from our well. Well, when I went to refill it the last time, there was this long twine or thread-like brown things which were wriggling about in the water. A few were loosely wound up around each other and a couple wriggling alone. I got rid of them immediately by dumping in the compost pile. Can you tell me what they were? I never saw such a thing before. And I hope it was OK to empty them and the water in the compost.

Charlie P.

A: I believe it was sometime back at least 10 years that I received a similar query. The answer will probably be similar as the name is the same: horsehair worm. When I first recall seeing these creatures, I was working (probably in 1957) at Pleasant Valley Sanctuary in Lenox, for renowned local naturalist Alvah Sanborn, then director. He explained that mostly old-time farmers would encounter these long, thick, hair-like animals, and some thought they were the result of horsehair falling into the water and coming to life. And when I looked it up in one of the many volumes he kept in his office, I learned country folk did indeed think these long living hairs may have come from horses and gave them that name.

You can go to YouTube and look up horsehair worms to see several interesting videos on this odd creature that belongs in the Phylum Nematomorpha family. One of the most common species in the United States, and probably what you had, is Gordius robustus, also named the Gordian knot. Worms come segmented, like the kind mentioned in the above, the jumping worms, and unsegmented, the horsehair variety, and like other worms they have a mouth up front and an anus behind. And these are aquatic.

No, birdfeeders do not prevent songbirds from migrating south.

Most important is that these are harmless! That is to dogs and cats and other mammals including livestock. Other animals including birds, reptiles and amphibians are safe too. On the other hand, many insects are at risk like beetles, grasshoppers, crickets and others. And an infected grasshopper or cricket may be what brought the worms to your trough. I have been told or read about bird baths, dog water bowls, and pails of water having worms.

The horsehair name comes from the superstitious belief that they were animated horse hairs. I must admit that I have seen few of these worms, and aside from those at Pleasant Valley, the only others I saw were at my wife’s grandfather's house who pointed them out in his dog’s outdoor water dish and thriving in it, although, there were no horses within miles.

Reader comments about 'jumping worms'

“I discovered jumping worms in my front yard and front gardens this summer. I live in Pittsfield. I did the mustard test and captured many worms in a plastic bag and put them in my garbage can. The next day the smell was horrendous! I dug up all of my perennials out front this fall to rearrange and found many more. I submerged them in a bucket of water and bleach to kill them. I would guess I found about 50 worms. I come across them from time to time in the lawn, as well, but in far fewer numbers. They are disgusting! I have gardens in the back, but have not seen them there. I did contact master gardeners and they asked me to send pics to greeninfo@umext.umass.edu. They responded and forwarded my email to Olga Kostromytska. Hope someone finds a way to eradicate them.”

Joanne W., Pittsfield

“I have been plagued with jumping worms here in Lee. I believed they have ruined my garden soil. Would love to hear what to do to get rid of them. Thanks for your great column.”

— Sally W., Lee

“I was interested to read your column about the [Asian jumping worms] today. It just so happens that I was at Richmond Center Cemetery on Thursday, working with my restoration team (including Ian Stewart from Ghent, N.Y.) on the 19th-century Williams family plot there. We were resetting old headstones, which involved digging in the ground there. A worm turned up, and my team told me that it was an AJW; they showed me its unique characteristics and mentioned about how it is an invasive that does not benefit the soil like traditional “nightcrawlers.” I garden at my home on Stockbridge Bowl. I don’t think that I have seen AJW’s here, but I will be on the lookout going forward.”

— Peter W.

“The worms are definitely here, probably coming in with mulch and compost. I am in Pittsfield, and I have them. A friend in West Stockbridge has them. I am a regular volunteer at the Berkshire Botanical Garden in the herb garden and we have had them there for at least three years. They are now common in most of the beds throughout the garden. You might want to talk with Eric Ruquist, the newly appointed horticulture director of the BBG. He reported to me that Garden in the Woods/Native Plant Trust has had them for 10 years and doesn’t think twice about it. I find them very distressing! But there is no solution at the moment. The herb gardener at Churchtown Dairy in Hudson (very interesting farm to visit!) suggested solarizing them and grinding them back into the soil — not sure I am with him on that one! I will follow your reports on this with interest.”

— Elizabeth L.


Thom Smith, NatureWatch columnist.

Get up-to-the-minute news sent straight to your device.