The Worm You Kill on Sight
We’re often told earthworms are a vital part of healthy soil. There’s one big, invasive exception.
Have you ever picked up a worm and had it immediately start thrashing around with seemingly uncharacteristic power? Chances are that it wasn’t a regular earthworm, but instead what’s often called a “jumping worm”. Chances are, too, that you got scared and dropped it — just as a predator might if it tries to eat one.
Three different worm species — Amynthas agrestis, Amynthas tokioensis, and Metaphire hilgendorfi — have come to be collectively known in North America as Asian jumping worms, crazy worms, “sharks of the earth” — or just pests. At a glance, they’re easy to mistake for the regular earthworms we’re used to having show up in our gardens and on our sidewalks. But that similar appearance belies a stark difference in their threat level to local environments.
So, what exactly makes them such a scary sight?
Super strength and speed
- Compared to most other worms, jumping worms have a much more muscular and sinewy body. That makes them much harder for predators to catch and hold onto.
- That bodily structure also makes them a less attractive option as prey. Birds, moles, and other vermivores would normally be happy to chow down on them, as they do other worms, but their tough texture can make them unpalatable — not unlike us trying to eat an uncomfortably chewy piece of meat.
Free “snacks”
- These worms have a few other defensive strategies up their sleeves as well. They can secrete a foul-tasting yellow mucus that will give any predator second thoughts about keeping one in its mouth.
- They’re also capable of autotomizing parts of their body, sacrificing a piece of themselves so the rest of the worm can escape, and eventually regrow. This latter maneuver is especially common with juveniles (which makes sense, since they’re already growing as is).
A voracious appetite
- Jumping worms can cleave through leaf litter, crops, and other plant matter at incredible speeds. This can lead to quick soil degradation and outright habitat destruction, displacing both native plant species and the animals that rely on them.
- If a species needs lots of healthy plant material for food and shelter, jumping worms can easily deprive them of it, and even force them out of the local ecosystem in the most extreme cases.
Casting calls
- Worm droppings — or more euphemistically, “castings” — are often touted as a nutritious addition to soil that can help improve its health and plant-growing capacity. But it’s not just the nutrition that helps; their small pellet-like shape can also help aerate the soil, which helps air, water, and plant roots get in and stay in.
- Jumping worms’ castings, however, are so large that they turn the soil into a sort of sieve, making water run right through it. This degrades the soil in a second way; these worms can not only devour a patch of plants extremely quickly, but also prevent new plants from growing in their place.
Because of how easily they can devastate North American ecosystems, the general advice for dealing with jumping worms is to kill them whenever you find them. If you have a bucket on hand, drowning them in soapy water is one of the most effective tactics. More creative solutions can work just as well — freezing them, trapping them in a resealable bag, or even just cutting them apart into several pieces (if you’re feeling particularly sadistic).
But with attributes like these, it begs the question of how any place could have possibly survived them to begin with. Where did they come from, and how does their origin point deal with them on an ecological level?
If you’re curious about where they hail from, or what we can learn from their native countries’ resources on them, I’ve written about that in a separate article here. It also includes more substantial tips on how to identify a jumping worm without resorting to picking it up and seeing how hard it starts squirming around.
Meanwhile, if you’re looking to do your part in stopping these invasive worms from doing major damage to local ecosystems, I have a guide on how to accomplish that here. It includes both tips on how to keep them from reaching new places, and advice on how best to remove them once they’ve taken refuge somewhere they don’t belong.
But regardless of whether you’re dealing with them yourself or not, it’s a good idea to stay aware of them, and know just what makes them so threatening. If nothing else, simply knowing that not every worm is as helpful as it lets on is important in its own right.
