Help with invasive worms in Denver

Question: Hi! I am a garden designer in Denver and have a client with a unique problem. We have been planting and adding to their garden for a few years now and have noticed plants declining and dying without explanation. I have done a soil analysis through the extension and all conditions seem to be excellent for planting. However, we discovered that most areas of the garden are riddled with hundreds of worms, which very much look like invasive Asian Jumping worms. The first 2 inches of soil are nothing but worm castings. I have attached a picture here for ID. Thanks for any help.

responder: An Ask Extension Expert Replied September 11, 2024, 3:39 PM EDT
response: Hi Russell, I agree that it's an Asian Jumping Worm (based on the location and color of the clitellum). Unfortunately, there are currently no viable jumping earthworm control methods (but research is ongoing). Management hinges upon stopping their spread, and there are some methods that can be somewhat effective. Now that your area is known to be infested, avoid moving soil/plants from there to other areas. Tools/boots/tires used in that area should have all the soil removed from them before being used in new areas. Hand-pickingCollecting and killing the worms on sight is an option, albeit labor-intensive. Worms that are caught can be left in the sun for several hours to kill them. Once dead, the worms can be disposed of without fear of spreading them to new areas.  To make hand-picking easier, use a mustard pour (which is totally harmless to plants). Mix a gallon of water with 1/3 cup of ground yellow mustard seed and pour slowly into the soil. This will drive any worms to the surface where you can easily remove them.Soil SolarizationUsing a clear plastic tarp, completely envelop soil and leave it in the sun so the mass reaches at least 104°F for at least three days Let me know if you have further questions.

responder: The Question Asker Replied September 16, 2024, 6:24 PM EDT
response: Thank you for the ID and the information regarding management. I haven't heard of these being an issue in Colorado yet- I am a little concerned since the worms have seemingly infested the entire property. We are worried that this will spread to neighboring properties and eventually will become a larger issue than one backyard. If there is anything that we need to do to avoid larger environmental impacts, please let me know. Thank you. On Wed, Sep 11, 2024 at 1:39 PM Ask Extension <<personal data hidden>> wrote:

responder: An Ask Extension Expert Replied September 23, 2024, 5:44 PM EDT
response: Hi Russell, I must apologize, I didn't do enough due diligence on this question. I was trying to figure out if these were Asian jumping worms, or common earthworms. I didn't consider that they may be another species, since the former are not known to occur in CO (yet). I have forwarded your images to the CO Department of Agriculture for identification and will let you know as soon as they reply to me (by replying to this question again). Until then, the management practices I've already outlined are the best things you can do.

responder: The Question Asker Replied September 23, 2024, 11:31 PM EDT
response: Thank you. I’m attaching a short clip of their movement if that would be helpful.  Sent from my iPhone On Sep 23, 2024, at 3:44 PM, Ask Extension wrote:﻿

responder: An Ask Extension Expert Replied September 25, 2024, 2:59 PM EDT
response: Hi again Russell, It turns out I was wrong, those are not Asian jumping worms. My contact at the CO Dept of Ag has identified your worms as Lumbricus rubellus, the redhead worm. This is a close relative of the common earthworm (Lumbricus terrestris), and it's not really worth being concerned about.