“This morning I found a live caterpillar or worm”, states this reader in California, who attached a photo of a large, brown caterpillar. She stated that it “looked like the Noctua pronuba caterpillar burrowing into the fleece fiber of my dog’s bed.” We cannot attach the same photo our reader did, as it was not her photo, but the caterpillar is brown in color, with green markings along its sides, and a light gray side going down the middle of its back. She adds that it was approximately an inch in length.
“I didn’t think to take a photo before removing and ‘releasing’ it on the hillside”, she continues. “To the best of my recollection, it resembled a Noctua pronuba caterpillar. I’m afraid I didn’t even notice if it had legs, I just wanted it out of the house quickly. I am writing to ask if it could have been some other kind of caterpillar or worm. Is it unusual that a caterpillar would be burrowing into the synthetic fiber of my dog’s bed? It’s head had burrowed 6-7mm deep; I had to pull it out of the fabric to remove it. This is a 100% polyester fleece dog bed with 100% polyester fiberfill. The bed had been washed and dried on high heat about a week ago. Could this be some kind of infestation? Would you recommend washing the bed again? The dog bed is usually kept on the floor indoors, up against an unused door to the outside, but which is pretty well-sealed, and while an ant could easily crawl through from the outside, this seemed too large to get through. I also take the bed outside onto my balcony so my dog can join me, but there are no plants. Could a bird have dropped a caterpillar? The bed was last outside yesterday morning. I guess bringing it in on our shoes, pant legs or the dog’s feet are also possibilities? Thank you very much for taking the time to read my questions.”
To that we thank our reader for sending in these questions in the first place! Now, when it comes to the Noctua pronuba caterpillar, better known as the large yellow underwing caterpillar, it is indeed very unusual for them to burrow into synthetic materials, or really any materials at all. That said, it is not unusual for caterpillars in general, as there are species that will perform this type of behavior, such as the clothes moth caterpillar. However, clothes moth caterpillars are white in color, and do not look at all like the caterpillar our reader describes. The large yellow underwing caterpillar is a type of cutworm, and their preferred diet is plants. The name ‘cutworm’ comes from these types of caterpillars’ tendency to specifically chew through the stems of plants, hence cutting them down.
So, in short, we find it strange that this caterpillar was found inside the dog bed. Perhaps there was already a hole in the bed, and the caterpillar ended up in it accidentally? In terms of how it got in the home in the first place, all of the suggestions our reader made are all plausible. Now, to answer her other questions about a possible infestation, we would say that this should only be a concern if she is finding a lot of the same caterpillars, especially in the same spot. But from what our reader stated, she only found the one caterpillar. Of course, if she is really concerned, then there is no harm in washing the bed again. Our guess is that it ended up there accidentally: perhaps her dog brought it in, as suggested, and the caterpillar ended up on the dog bed and went into the hole to try and escape. Or maybe it did indeed make the hole itself to try and hide, resorting to unusual behavior in a desperate attempt to avoid the big scary dog.
To conclude, we cannot say for sure what the caterpillar our reader found was, as she did not provide pictures of the one she found. But if it indeed looked like a large yellow underwing caterpillar, then it is likely that it was that, because there are no species of textile-eating caterpillars (that we know of) that look like a large yellow underwing caterpillar. We hope this article helps and we wish her the very best.