“Found these in our storeroom, mostly in and on a suitcase and on a box next to it”, writes Mark about the pink worm-like creatures pictured below. “They are about 1/2 an inch long. Many were in a white web-like cocoon. We are in the SF Bay Area. Do you know what they are? Thanks.” To start with, we want to thank Mark for the excellent photo he sent us. We can clearly see the creatures, as well as the webbing he describes. Based on this photo, as well as the context provided, we have identified these are clothes moth caterpillars. In particular, we think these could be webbing clothes moth caterpillars.
As their name suggests, webbing clothes moth caterpillars produce their own webbing, which comes out as a silk-like string. They secrete this webbing, which is somewhat sticky to the touch, on the textile items that they feed on, so as to get around easier. And, like Mark suggests, they also do use this web to eventually construct their cocoon when they are ready for pupation (the process by which the caterpillar transforms into a moth). But, before they build their cocoon to metamorphose, the caterpillar needs to store up enough energy to do this. How do they do that? By eating. Voraciously.
We mentioned that they feed on textile items, and they particularly like those made from natural fibers: wool items are the most at risk, but cottons, silks, and even feathers and leather are also at risk of infestation. When the caterpillars infest a textile item, like they’ve done to the suitcase in Mark’s photo, they can cause significant damage to it, chewing holes through the fabric and leaving behind webbing and faecal pellets. That is why it is important to eliminate an infestation as soon as it is discovered. The best way to do this is to clean any infested, and potentially infested, items. Usually that includes laundering and vacuuming, though that might be hard to do for a suitcase. In this case (pun intended) we would suggest hand-picking the caterpillars off, and then, if possible, vacuuming the outside of the suitcase using the nozzle of the vacuum (or a smaller extension if Mark has one). Likewise, Mark may want to check the rest of the storeroom for more caterpillars and vacuum the entire room, just to be sure that any eggs or larvae that would otherwise go unnoticed get eliminated.
In conclusion, we think that the worms Mark found on his suitcase are webbing clothes moth caterpillars. They are not harmful to humans or pets, but they can cause significant damage to textile items. We hope this helps, and we wish Mark the very best!
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