Outdoors: Invasive jumping worm used by anglers threatens native worms

By Kym Pokorny

Oregon State University Writer

Jumping worms, a not-so-nice pest that arrived in the United States in the 1920s as fishing bait and as hitchhikers on imported plants and soils, have vaulted into gardens and nurseries up and down the Willamette Valley corridor.

Unlike beneficial earthworms and nightcrawlers that burrow deep tunnels in the soil, aerating and releasing nutrients as they go, jumping worms stay in the debris on top and eat two to three times the amount of leaf litter as the other worms, according to Sam Chan, Oregon State University Sea Grant Extension watershed health and aquatic invasive species specialist.

Jumping worms, which are native to many parts of Asia, are easily identified by their violent thrashing, slithering and actual jumping in the air. They are smooth, glossy gray or brown and 1.5 to 8 inches long. A clear indication is the clitellum (band), which is milky white to gray-colored, smooth and completely encircles the body of the worm. In contrast, the clitellum of common earthworms is raised rather than smooth and does not wrap entirely around the worm.

Because they have very large mouths akin to mechanical excavators, jumping worms are able to grasp and consume large amounts. With their voracious appetite, they outcompete the native microbial organisms and invertebrates that other organisms feed on. Their propensity to eat all the litter creates bare soil where invasive plants and animals move in, altering native ecosystems. They also remove the mulch that helps cool the soil and conserve moisture,

Further, the castings – or fecal material – of most worms contain extremely important microbes that help fight soil-borne plant diseases and repel insects. Worm castings also improve soil structure by diversifying the size of soil particles, which enhances moisture penetration and increases water retention. With jumping worms, the outcome is the opposite. Since their gut biome is slightly different, there aren’t the same beneficial results.

“What they are casting out doesn’t absorb moisture well so you end up losing porosity, which affects the overall structure of the soil,” Chan said. “Initially wet and gummy, the castings quickly dry into hard granules that are difficult to rewet, not the best medium for growing plants.”

The changes to soil structure and composition caused by the worm castings can attract certain unwanted microbes, which creates an increased susceptibility to disease and can cause girdled roots. Plant stems and roots at the surface of the soil may become exposed to more environmental extremes from the loss of litter and decomposed organic matter and changes to soil structure.

It’s difficult to put numbers to the amount of jumping worms in Oregon, Chan said. The first – an Amynthas gracilis – was found in 2016 in Grants Pass, where it was passed along through compost. Another species – Amynthas agrestis – has landed in at least six counties, from Pendleton in the east and to the I-5 corridor down to Roseburg, all on major transportation routes. Most likely they arrived as tiny cocoons in plants, soil, mulch and tire treads from the East Coast, where they do extensive damage to forests. Gardens suffer, too.

Since they are both female and male, jumping worms have no trouble reproducing. They burrow into the soil and lay tiny cocoons with two or three embryos inside. The cocoons hatch in spring, begin feeding, grow rapidly into adults and die in winter after laying more cocoons. The next spring, it starts over again.

Jumping worms have been outlawed in many states, but not all, and can still be found online for fishing. Chan advises to be careful not to purchase jumping worms, also known as crazy worm, Asian jumping worm and snake worm, and to spread the word about their danger. Many people – even those who sell them – aren’t aware of their invasiveness.

If you find jumping worms, report it to the Oregon Invasive Species Council’s hotline 866-INVADER (268-9219) or online.

* * * * *

ODFW has released a final proposal for changes to how archery elk season is managed for portions of eastern Oregon within the Blue Mountain region.

This final proposal includes two major modifications from the original draft proposal released in March: Five units would be combined into a single Eagle Cap Zone hunt and there would be a single general season hunt for any part of the state not proposed for controlled hunting, see a map on the big game review page for more information. (The original proposal was for a general Western Oregon and general Eastern Oregon tag for any units not managed as controlled hunts.)

These changes are needed to help wildlife managers meet elk plan objectives in areas with low bull ratios and in areas with a high percentage of branch antlered bull harvest occurring within the general archery season, the ODFW says. Current management strategy only allows managers to alter harvest during the controlled any legal weapon hunts, resulting in significant changes to the season structure and tag numbers for rifle hunting over the last 30 years.

This proposal will be presented at the Aug. 6 state Fish and Wildlife Commission meeting for potential adoption. To see the full proposal, see Exhibit B at http://www.dfw.state.or.us/agency/commission/minutes/21/08_Aug/index.asp.

Additional information about the big game review process can be found at myodfw.com/articles/big-game-hunting-season-review.

The Aug. 6 commission meeting will be online via Zoom. To testify about the proposal, register at http://www.zoomgov.com/webinar/register/WN_5F152fCyTdyidRFGazlDRw no later than 48 hours before the meeting (by 8 a.m. Wednesday, Aug. 4). Comments can also be sent to [email protected].

The remainder of the 2022 hunting regulations will be presented at the September Commission meeting.

More about potential changes to archery elk hunting: Under the proposal, 13 wildlife management units (WMUs) and three sub-unit hunts would move to controlled archery seasons (see map). These hunts would be added to the current seven WMUs within the Blue Mountains already managed for regulated archery seasons. These controlled hunts would be the only opportunity for archers who draw and purchase those tags.

WMUs not proposed for controlled hunts would remain under the current statewide general season framework, allowing archers to continue to move in response to conditions throughout the state during the archery season.

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