A little while ago we received a question from a reader about some worms she is finding in a pond. The pond worms are white and brown, although the proportion of each color varies from worm to worm; some worms are only slightly brown, with white serving as the worm’s main color, whereas others are almost entirely brown. (In any case, this is what we gathered. The email is a little hard to decipher; fractions like 3/4 are invoked to describe the worm’s colors, which is helpful, but it’s not always clear what color the fractions are referring to.) The reader also mentioned that the worms are small, in the 1/4 to 1/2 of an inch (6-12 mm) range. So, our reader is dealing with some small brown and white worms, and the question of course is: what are they?

All of the information our reader gave us is good. We know the size of the worms she is finding, and we also know (more or less) their color. Moreover, she described the place she found them – a pond – which for whatever reason is an important detail often overlooked by readers who submit questions. We definitely have material to work with. On the other hand, we don’t have any pictures of the creature our reader is finding, so our suggestions can’t be checked against a photo. Also, the reader added some information to her email that we aren’t entirely sure what to make of. She mentioned that tadpoles and salamanders are in the pond, but that they are now gone (or at least the salamanders are – the wording is unclear). She also says the worms she is finding might be dead, but then immediately says that this might not be the case. None of this seems to bear directly on her question, however, so we’ll leave it aside.

Although we are ultimately unsure what our reader is finding, we are fairly confident she is finding some type of larvae (which means our use hitherto of the word “worm” is technically inaccurate). One possibility that immediately comes to mind is the moth fly larva, which we have written about many times, but only when addressing someone who found them in his or her home. Moth fly larvae are commonly found in places like toilets, particularly ones that are infrequently used because these allow the water to remain stagnant. In general, ponds have fairly stagnant water, and of course moth fly larvae exist in the outside world, so it’s certainly possible our reader found them in the pond. Moth fly larvae also have bodies that might be described as white and brown, and in varying degrees. Often the brown parts look like stripes, and there can be so many that the body does appear more brown than white. It’s also possible our reader found crane fly larvae, which commonly live in ponds. However, crane fly larvae don’t really have white on their bodies (they are essentially different shades of a brownish/grayish color), and they can also grow to sizes much larger than what our reader described. Moth fly larvae, conversely, are about the size of the creatures our reader found.

Unfortunately, that is all the information we can supply. It seems reasonable that our reader found moth fly larvae based on all that has been said, but we are far from certain this is correct. However, regardless of what our reader found, we think there is a good chance she found some sort of larvae. Tons of insects make use of ponds to lay their eggs, which means there are lots of different larvae in ponds. Our reader should therefore consider looking into the various types of larvae found in ponds, perhaps starting with moth fly larvae to see if we are correct, but then exploring other types if we missed the mark.

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