Garden Word of the Day
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Asian Jumping Worms
With a name like Asian jumping worms, you might expect colorful, flamboyant gymnastics moving gleefully through the soil, helping your plants grow.
Okay, that was a stretch. And you’d be mostly wrong.
I say mostly because, while not colorful, these worms really can move. Also known as snake worms, crazy worms, and Alabama jumpers, Asian jumping worms writhe violently when disturbed. They can even drop their tail when threatened.
Sadly, instead of helping plants grow, these voracious feeders strip an area of nutrients, destroying the top soil layer, and leaving desolation in their wake. This interrupts thousands of years of evolution and nutrient cycling, threatens biodiversity, and increases erosion.
The invasives mixed bag
Before we get into the Asian jumping worm story, let me remind you that our beloved European nightcrawlers and honey bees are also non-native species. Sometimes invasives can be a good thing. This is not one of those times.
As with many other situations involving invasive anything, the problem lies in imbalances. North American forests and farmlands have evolved, over thousands of years, to use surface plant litter as slow-release food and secure habitat for countless microorganisms, insects, reptiles, amphibians, and other life forms. Asian jumping worms eliminate that layer and they do it very quickly.
What are jumping worms?
Our more sedate earthworms tend to be reddish brown with a raised white or gray partial band part way down the body. That band is called the clitellum. Asian jumping worms, which can range from 3 to 7” long, are gray to dark brown, with a smooth the clitellum that goes all the way around and is closer to the head end.
Also, while shiny, jumping worms do not produce the slime seen on many earthworms. Regardless of how you feel about that slime, it is very useful in creating soil aggregates that allow for the healthy movement of air, water, microorganisms, and roots through the soil. Jumping worms also tend to be more rigid than our squishy earthworms.
There are three species of Asian jumping worm: Amynthas agrestis, A. tokioensis and Metaphire hilgendorfi, with A. agrestis being the most commonly seen. Native to Southeast Asia, jumping worms are believed to have been brought to North America in potted plants, bagged soil, or nursery stock, though we don’t know exactly when or how.
Asian jumping worms have moved quickly westward, in worm terms, over the past 10 years and are now found in Oregon. As you can imagine, these continued movements are not just worms traveling on their own. Asian jumping worms end up in plants, mulch, and soil, on shoes and equipment, in agricultural produce, and in batches of fishing bait. They get transported by us, one gets loose, the problem spreads. It’s easy to do because these jumping worms spend their winters as tiny, pinhead size cocoons, filled with eggs, they reach adulthood twice as fast as our familiar earthworms and red wigglers, reproduce more rapidly, and are more aggressive. They can also thrive in higher densities and eat a wider variety of foods.
The real problem with Asian jumping worms is where and how fast they feed.
Damage caused by Asian jumping worms
Asian jumping worms are too efficient. That may sound like a good thing, but too much of a good thing can be a bad thing. Let me explain.
As earthworms feed on fungi and bacteria that grow on decomposing organic material, they burrow into the soil, excreting castings that are filled with broken down plant and animal material, churning the soil and improving soil structure, soil health, water retention, drainage, and nutrient cycling. Everybody’s happy. Plants and organisms grow. Life goes on.
Asian jumping worms are eating machines, quickly devouring all of the surface material in an area and leaving behind a trail of low-nutrient crumbles prone to serious erosion. Research has shown that jumping worm castes are different from those of other worms. Instead of the soft, brown, crumbly bits of plant food and soil amendment we associate with earthworm castings, Asian jumping worm castings look more like a pile of coffee grounds.
Asian jumping worms process nutrients so rapidly that their feeding releases nutrients faster than plants can absorb them, causing the nutrients to be washed, blown, or leached away. These castings contain important plant nutrients, such as potassium and calcium, and they tend to contain higher levels of heavy metals, such as iron and aluminum. When those crumbles are eroded away, those nutrients are lost. As a result, Asian jumping worm feeding quickly converts healthy, loamy soil in to granular, more sandy soil that tends to be hydrophobic, which means water runs off instead of sticking around long enough for plants to absorb. These invasive worms also push nutrients so deeply into the soil subsurface that many shallow-rooted plants cannot reach those important nutrients, leaving them to starve.
What can you do about jumping worms?
In a word, be diligent. Asian jumping worms generally cannot survive freezing winters, but anything less than that and they can become a serious problem in your yard. You can help prevent the spread of these invasive worms with these handy tips:
Bottom line, earthworms create topsoil while Asian jumping worms destroy it. Of course, that’s an oversimplification, but I want you to understand how important it is that these pests are kept in check.
If you suspect the presences of Asian jumping worms in your garden, conduct a mustard test using these steps:
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