“I had a large moth in my bathroom about a week ago”, writes Ed in his submission regarding the tiny, black, worm-like creature pictured below. “Two days ago I went into my bathroom and the sinks were covered with hundreds of miniature worms, that I would call inch worms from their methods of movement. I wiped up all of these with wet tissue and threw it into the toilet. Much to my surprise the next morning they were back again! Same for today! The sinks are used daily, so there is water in their traps. Where are these coming from and what are they? I’ve attached pictures with a sewing needle for determining scale.”
To start with, we want to thank Ed for the great photo and the ample context: both really help us pin down the identity of the creatures we work with. In his case, we think it’s possible he’s dealing with armyworms (armyworm moth caterpillars), though they could very well be another species of caterpillar. In any case, they are clearly newly-hatched caterpillars, which is suggested by the sudden and large number of caterpillars seemingly spawning out of nowhere, as well as by their size. They do resemble newly-hatched armyworm caterpillars: their bulbous, black head, dark gray coloration, and clear segmentation point to this.
Armyworm moths are not necessarily very big, but they can grow to an inch in size, which is large in our opinion. It is odd, and unlikely, that an armyworm moth, or any moth for that matter, would lay their eggs inside a sink or drain, as it does provide an ideal, or safe, environment for the eggs to hatch. We doubt the eggs were laid there in any case, since, as Ed said, the sink is regularly used, so the eggs would have been washed away before they had a chance to hatch. We think it more likely that the eggs are somewhere else in the bathroom, perhaps directly above the sink. If there is a cabinet/cupboard above the sink, check the underside of it! Armyworm moths typically lay their eggs on a flat surface, and will typically do this on walls and ceilings: it might be worth checking there too.
Additionally, the eggs might be hatching at different times, which is why Ed is finding new ones every day, even after flushing the caterpillars down the toilet. On that note, we want to urge Ed to stop flushing the caterpillars down the toilet. They are harmless creatures, and can simply be moved outside to the same effect. They will not purposefully invade Ed’s home again, as armyworm moths only lay their eggs in people’s homes as they provide stable environments and shelter for their eggs to hatch. Armyworms have no real interest in anything inside a home: they feed on crops and plants that cannot be found indoors (they haven’t even been recorded eating houseplants!).
To conclude, we think it’s possible that the tiny, black worms Ed has been finding in his sink are newly-hatched armyworms, or at the very least, some type of caterpillar. They are harmless critters, so we advise against flushing them down the toilet. We hope this helps, and we wish Ed the very best!
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