Hello Vanessa,

We don't recognize the worm or know why it's this color, but we're reaching out to a few biologists to ask if this is either a known exotic species or perhaps a local species with a known condition that has changed its color. We'll be in touch again once we get responses.

Miri

Hi Vanessa,

We have received replies from our contacts and have some interesting information!

Several species of earthworm naturally have green color forms ("morphs") like this, but one local scientist believes this individual is either Allolobophora chlorotica, a species introduced from Europe, or Amynthas hupeiensis, a species introduced from Asia. (Neither has a common name.) Based on this worm's size and its darker green color, she thinks this worm is A. hupeiensis.

Most of our local earthworms are non-native or invasive, but these are not new to our area. According to a publication about Asian worms in North America and their identification, this species was recorded in D.C. back in 1910, and likely arrived via the introduction of the Asian flowering cherries planted at the Tidal Basin.

Maryland Biodiversity Project catalogs organisms found in the state, and while they do have pages for each of these two worms [species name links above], they have almost no photos and few records. If there is a way to photograph the worms such that they can be identified to species from the photo(s) alone, you could submit them for county records. (We don't yet know what physical features would need to be clearly visible. You may need to inquire with MBP. They do glean images from iNaturalist submissions, for example.)

This researcher hopes to use citizen science in a study of earthworm distribution in Maryland, both in the form of photos and physical samples, so perhaps you can submit worms once her program is up and running later this season/year. Master Gardeners might be playing a role in the outreach, so you can check-in with your county coordinator in a month or so to ask about participating if you're interested. (We don't yet know exactly when or how her project will begin.)

As for "good" vs. "bad" on their being in your garden soil, we'd say they may be somewhat "bad" in the sense that they're not part of our ecosystem, but they are not expected to be causing undue stress to your plants. Jumping worms, cousins to one of the two species above (some are in the same genus), can be more problematic when numerous in garden and woodland soil.

Miri