“I found this thing apparently crawling away from a scene of carnage in my dining room in Fayetteville, NY, not far from Syracuse”, writes this reader in his submission regarding the black, segmented worm-like creature pictured below. “One of my cats got a mouse, started eating it, but apparently was grossed out and threw up not far from the headless corpse of the mouse. In the process of cleaning that up, I noticed what I thought was a small cat turd about 3-4 ft away, but as I picked it up with a paper towel, it moved. And it appeared to have crawled away from the kill site.
“Initially I thought it must be some sort of parasite from the cat or the mouse that was trying to escape, but now I think it might be a soldier fly larva or prepupa, but I don’t see any hairs/bristles on it. It’s about an inch long most of the time, about 1/3 inch wide most of the time, moves with undulation, and has distinct mouth and anus type orifices, at least one of which can project some sort of pincers or mandibles. It moves around in the plastic bag I put it in quite well. What I can’t figure out is what it was doing in the area. Could the mouse have been carrying it as a meal? Is it a parasitic organism after all? Then there’s the question of what to do with it. I don’t feel right killing it since I’m pretty sure it’s harmless, so I’m leaning toward releasing it in my yard as far from the house as possible.”
To start with, we want to thank our reader for the comprehensive context and the fantastic photo and video: they give us a detailed look at the organism in question which helps us identify the organism. That said, our reader has already done our job for us, as we agree that this looks like a black soldier fly larva, which is what we think it is. And props to him for identifying it at the prepupal stage: its black coloration also seems to indicate this. Younger black soldier fly larvae will be a beige color. We think that the “pincers” our reader noticed may just be its mouth.
Now, the big question is why did our reader’s cat presumably throw it up? Black soldier fly larvae are not parasites (they are actually excellent composting worms), so they would not have been inside the mouse the cat was eating. Our guess is that some black soldier fly larvae have found their way into our reader’s cat food, and that the cat throwing it up along with the mouse was a coincidence. Black soldier fly larvae have been known to invade people’s homes and start munching on the food in there: they are really not picky eaters. We recommend that our reader check the cat food for any more roaming larvae, and that, if he finds them, he throws it out. Black soldier fly larvae are safe to consume, but his cat may not want to be ingesting their faeces.
Lastly, we think our reader’s instinct to not kill the organism but move it outside, far from his home, is exactly right, and that is what we recommend all of our readers do when they find an unknown organism in their home. It is best to assume they are harmless, just in case they may be important benefactors of the environment, which black soldier fly larvae are.
To conclude, we agree with our reader that this is a black soldier fly larva. Of course, if he does believe his cat may be suffering from parasites, he should take his cat to the vet. In any case, we are not qualified or legally able to identify parasites since we are not medical professionals. We hope this helps and we wish our reader the very best!
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