A little while ago a reader wrote to us about some white worms with a green spot that “appeared out of nowhere” in his basement. The reader got rid of many of the worms in the basement by taking them outside, but when he got back there were even more worms than there were before. The reader said the creatures in the basement looked like inchworms, but he didn’t seem very confident in this suggestion. He also mentioned that it was raining out when he made his discovery, and thought this might have something to do with the worms’ sudden appearance in the basement. What might the white worms with green spots in our reader’s basement be?
As happens fairly regularly, the various components of our reader’s email/question pull us in different directions. When he mentioned that the problem was largely confined to his basement, we thought he might have found millipedes, as these are a common worm-like creature people find in their basements. However, the colors of the creatures he found – white with a green spot – essentially rule out this suggestion, as does the fact that the reader didn’t mentioned that the creatures he found have tons of legs. (When people find millipedes, this is one detail that generally isn’t omitted.)
The outward appearance of the creatures suggests that he might have found some sort of caterpillar or other sort of larva, but without any sort of picture to get a true sense of what this creature looks like, it is extremely hard to say exactly what he found. He could have found, as he himself suggested, one of the tens of thousands of different species of inchworm, which are caterpillars, but we have no way to confirm this, let alone identify the exact species he found. He also might have found some sort of fly larvae, whose bodies are often white (think of maggots), but we don’t know of any fly larvae that are white with a green spot, which, again, is the type of vibrant, noticeable body feature associated with caterpillars.
One thing we should note is that although worms are known to come out after it rains, it is pretty clear he didn’t find any sort of worm, despite his use of the term throughout his email (and our use in the opening paragraph, which we did to match the language of our reader). Although lots of worms (mostly earthworms) come out after it rains, these are not the types of creatures that generally make their way into houses, and in fact the relatively dry interior of a house is the last place they would be inclined to go when there is a bounty of moisture to be enjoyed outside. Moreover, earthworms are almost always a brownish, reddish color, and even though they can be somewhat pale, none that we know of are white with a green spot. That said, the rain may be relevant to our reader problem, as several types of larvae and insects are driven indoors in response to changes in the weather. This doesn’t lead us toward any sort of identification in this case, but it is worth mentioning because it means that the reader’s problem may be temporary (plus he specifically asked about this).
Unfortunately, that is really all we can say about our reader’s question. We don’t have enough information to make an identification, and the information we have leads us in different directions. So, all we can say to our reader is that he almost certainly didn’t find worms, and he may have found some sort of caterpillar. Also, the presence of the creature could well be related to the rain, so the problem could subside when the weather normalizes.
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