A little while ago, a reader from New Jersey sent us a query about worms in her back yard. The worms come out at night, especially if it is damp. The backyard worms are described as rather large – the reader estimates that they are six inches (about 15 centimeters) long, and that they are as wide as her little finger. Evidently the worms shy away from light, so the reader has been unable to take a picture of them. The worms don’t wriggle like a common “garden worm,” to use the reader’s unfortunately vague phrase, but instead move like a whip. If the worms are causing any damage, the reader does not mention it, but she does describe them as “truly gross” and says that her neighbors refuse to sit in her backyard because of the worms’ presence. The reader is wondering what her backyard worms are, and also if she should consider taking actions to get rid of them.

The reader supplied us with a lot of information, but it is unfortunate that we don’t have a picture to consider. As we’ve explained many times before, we can’t simply identify any given creature in a photograph, but it at least gives us a way to narrow the possibilities and check hypotheses against concrete data. So, we’re left to speculate without the constraints imposed by a picture.

In truth, though, our speculations about the creature our reader found are anything but exotic, as it sounds a lot like our reader is dealing with regular earthworms, also known as nightcrawlers. They sound like somewhat large earthworms, but not strangely so. (There are some species of earthworm that can reach multiple feet in length.) Why have we arrived at such a pedestrian answer?

First, the reader mentions that the worms are coming out at night, which is exactly when you would expect nightcrawlers to come out. Worms cannot endure much sunlight (this is perhaps why the worms were sensitive to the reader’s light source) because their bodies need to remain moist to breath, so they often come out at night. This also explains the reader’s observation that worms are particularly prevalent when it is moist outside. Finally, earthworms are obviously extremely common, and it is more likely that our reader found a common worm than an uncommon one.

The one consideration that gives us pause is that the reader explicitly dismisses the possibility that she found a “garden worm,” by which she might have meant an earthworm. When people think of generic worms, they often think of earthworms, as we touched on in our article “What is a Worm?” Then again, the reader might not have meant an earthworm. We simply don’t know. Tied to this concern is the fact that the reader connected the worms’ movement to her conviction that she didn’t find a “garden worm.” She said the worm moved like a whip, and didn’t just wriggle. However, we don’t really know what to make of this, as an earthworm might move in a way that could reasonably be described as whip-like, especially when picked up (which is what the reader did to the worm when she observed its “unusual” movement).

So, to conclude, we have to stick with our guess that our reader found an earthworm in her back yard in New Jersey. (The fact that she lives in New Jersey does not compromise this guess either, we might add.) Based on what we do know, earthworms seem like the most likely possibility, despite the reader’s suspicion that she didn’t find a “garden worm.” And if she is only dealing with earthworms, there is certainly no reason for her to seek to eliminate them from her yard (rather, she can enlighten her neighbors as to the benefits of earthworms). Indeed, earthworms are good for yards because they help aerate the soil when they move through it.