Subject: Molting aquatic life form
Location: Lucas County, Ohio
March 6, 2015 12:37 pm
One of my volunteers found this insect (I think), molting in her collecting tub of vernal pool water in mid-July in NW Ohio. The pool is isolated, nowhere near a creek, pond, or lake. The attached pictures are 20x if I remember correctly (other option is 40x) and were taken in the field. We watched it struggle free of the larval skin under the microscope. The skin shape reminds me of a damselfly nymph. Could this possibly be the pupal form? I’ve tried to count legs of both larvae and the skin, magnify head shape etc, but I am still stumped.
Signature: Eileen
Dear Eileen,
We cannot say for certain what creature this is, but we have some thoughts. If the tub collected rain water, any insects present would need to have either developed from an egg laid by a flying insect or been transported from another water source on the bodies of a bird or other creature that visited the pool. This creature reminds us somewhat of an aerial view of a mosquito tumbler, the pupal form. Most images online are side views, but BugGuide does contain an aerial view that looks similar. We hope someone more skilled at aquatic identifications can provide some input.
Hi Daniel,
Thanks for the reply. This was found in a collecting bucket, about a
quart of water taken from a huge vernal pool that has a wild egg bank
in the bottom of the pool when it is dry. I agree, it does resemble a
top view of a mosquito tumbler. It was definitely squirming out of the
nearby exoskeleton though, and the legs on that shell have spurs on
them – not found on mosquito larvae. It’s always possible that larvae
can get caught up in other exoskeletons as they’re wriggling about,
but in the one picture there are definite legs on the new critter.
Thanks very much for trying. I use this as an example for my
volunteers – there is always something new to be found in a vernal
pool and it can’t always be identified!
Eileen
