High School Science Experiment produces unknown Larva!!!

Subject: What is this bug?
Location: Jamestown, Tennessee
October 10, 2013 10:56 am
I’m a high school senior this year and currently enrolled in a Biology II class. We recently did an experiment where we placed decomposing leaves in a mesh bag and let our leaf packs sit in water for three weeks. When we opened our leaf packs today, this bug was in our packet. No other group had anything like it, and our teacher could not identify it. Do you know what this could be?
Signature: Alex

Unknown Larva
Unknown Larva might be a Hellgrammite

Hi Alex,
Unlike your Biology teacher, we do not have a background in natural sciences.  We are very curious what this experiment was supposed to produce.  What kind of water were the leaf packs sitting in?  Was it distilled water or were the packs tossed into a lake?  Since the packet was under water, this larva must be aquatic.  At first we thought it was a Hellgrammite, but upon enlarging the thumbnail that was attached to the email, we realized that the appendages typically present along the abdomen of Hellgrammites, the larval form of Dobsonflies, appear to be absent.  The head of your larva does appear quite similar to the head on this Hellgrammite posted to BugGuide.  Perhaps one of our more knowledgeable readers will correct us, but we are still leaning toward this being a Hellgrammite.

2 thoughts on “High School Science Experiment produces unknown Larva!!!”

  1. The mandibles are very megalopteran (like a dobsonfly or fishfly), but it’s difficult to decipher the appendages that should be at the end of the abdomen. Definitely need more info on the kind of water the leaf pack was placed in, where the leaves came from, etc. Megalopterans need oxygen from flowing water, so this critter may actually be an aquatic beetle larva of some kind, which can tolerate lower oxygen levels.

    • Thank you for your input. We never received any further information, and we are still quite curious what this “experiment” was expected to produce.


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