“What are the little black maggot-looking larvae that are in creeks?” asks Crystal in her submission. “They live under leaves and they are only in creeks once a year. I used to fish with them but I don’t know what they are.” Crystal does not attach any photos to her submission, which makes it much harder to narrow down the list of suspects for this creature that Crystal is searching for. Unfortunately, there are a lot of worm-like creatures that fit Crystal’s description. They could be anything from millipedes to rosemary beetle larvae to leeches. With that said, we have tried to narrow down our educated guesses to two species that are more “maggot-looking” than the others, and which tend to live near creeks and streams.
The most feasible suggestion is that these are black fly larvae. Black flies belong to the genus Simulium, and their larvae, generally speaking, live in bodies of fresh water: specifically in flowing water like creaks, streams and rivers. In fact, if the water in the given stream is clean enough, you can see the larvae at the bottom sticking straight up from the ground. They do this because of how they eat: as the water flows by them, they feed on the nutrients in it, making them ‘filter feeders’. They are basically live sieves. The adult flies are relatively harmless, despite technically being ectoparasites (parasites that feed on the outside of their hosts, like mosquitoes). Depending on the species, they will bite humans, other mammals, and even birds. They are very common on farms, where they love to annoy the cows, horses, goats, and other barnyard animals. We should note that black fly larvae do not live under leaves, but they are black, vaguely maggot-like, and they do live in creeks.
Our other suggestion is that these are black soldier fly larvae (BSFL), which is not the same thing. The adult black soldier fly larva does not bite people, nor do the larvae live in aquatic habitats. These guys are benefactors of the environment. Like earthworms, they eat decomposing organic materials, thereby breaking them down faster, and excrete nutrient-rich waste that is healthy for soil systems. They are also highly nutritious, and are safe to eat for humans and animals; we should note that they do make good fish bait, and it was Crystal’s comment about fishing that got us thinking about BSFL. They do not exclusively live under leaves, but they live anywhere you can find vegetation and animals.
In conclusion, we cannot be sure what Crystal found without a photograph of the organism. Her description of the creature she found can be applied to too many kinds of worm-like critters that might live in this habitat. Our best guess is that these are either black fly larvae or BSFL. We hope this helps, and we wish Crystal the very best.
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