Are there trees above these wormy plants? If so, it could be a web nest above them that needs to be removed. Personally, I have never seen a hair thin, whitish worm, 3 inches long on my plants. What planting zone are you located in??

My zone is 6, I am in Canada (Southern Ontario). There is a tree near the area but I can't see any sort of nests in there. It's a possibility I guess.

They seem to only be around when the ground is wet or it rains, so next time that happens i'll try and grab one and take some pics.

Maybe a garden slug. Slugs are usually seen in very early morning when there is wet weather and its still cool and damp.

I was out gardening in a light rain on June 3 when I noticed a similar thing-- emerging from the mulch surrounding my tomato plants were thread-thin, smooth white worms, about 3 inches long, waving around blindly, and climbing anything they touched. One even wrapped itself around a tomato cage wire and climbed that. They were pretty energetic climbers, too. They had no feet-- caterpillars do-- and they were way too thin to be slugs.

I decided it was time to stop gardening for the day and crept into the house to look up "climbing worms" on my computer. I had never seen anything like it before, either, probably because that type of worm likes to come out in the rain. I had watered the day before, so the soil itself was already moist.

The worms seem to have been Mermis nigrescens, which parasitize grasshoppers. There is apparently a laboratory line of them from some discovered in a Canadian woman's garden, according to Google.

Mermis is a roundworm, and many roundworms are parasites. Mermis nigrescens is part of a larger group of roundworms called "horsehair worms."

I called my county agent (in Cumberland County, PA), and was told that without actually seeing a specimen, they could not assure me that the worms I saw were actually Mermis nigrescens, which is supposed to be harmless to humans, since it only parasitizes grasshoppers.

Mermis nigrescens is supposed to be beneficial, according to the articles I found through Google, in that it weakens grasshoppers, and research is being done to see if it can be purposely introduced in farm crops for that purpose.

Mermis climbs grass and leaves tiny black eggs on it for grasshoppers to eat. The eggs open up upon contact with water, hopefully within a grasshopper, which is then parasitized.

The extension agent said 3 inches was rather small for a Mermis, so the worms were probably just coming out to mate. The Google article I found suggested that they look darker when full of eggs.

I personally plan to use the tomatoes from that patch for tomato sauce, and the few herbs I have nearby for cooking as well, just in case it was not Mermis nigrescens.

I keep wondering if the same worms are coming out when it rains in my hubby's garden through our township. He uses the same mulch, and we eat lettuce from that one... :(

The most important question is- do you see many grasshoppers? Here, I have not seen such a worm, and have noticed very few grasshoppers. Of course birds like to forage through the grass too.

After googling Mermis nigrescens I have to say it seems almost certain that they are what I am seeing.

I'll take some pictures next time it rains.

Common name is Horsehair worm. Crickets, katydids, and other insects can be hosts, as well.

Is this similar? I came across this after a rainfall this morning and trying to figure out what it could be.

Hello I came across this page while trying to find what I saw In my garden today; and after reading your description, I've seen the same thing myself.

It's been raining all day and after it finally finished I went out to the garden to take a look at my flowers I've just taken up gardening.

when I looked at the plants I noticed these odd white worms they were thin with no eyes or legs and were moving about on the leaves I've never seen anything like them before so ran In the house asked my husband what he thought they were he said (invasion of the body snatchers) not helpful!

So I went back outside and made a video on my phone.

I think they are horsehair worms here is a link to my video

https://www.facebook.com/Melsywoo/videos/10152979561881417/

Hope this helps us find out more about these odd things.

Many thanks

Mel