Friday, July 13, 2012

18,433 Odonata Nymphs!

That's how many nymphs (larvae) were in samples from about 15 years of ecological sampling from Earl Werner's projects at the Edwin S. George Preserve (ESGR) in Livingston County, MI. The ESGR has been owned since the 1930s by the University of Michigan, and has been the site of many long-term projects. We recently received all of Werner's samples, and the contents of each jar is cataloged in a Filemaker Pro database. I did a search for Odonata, and found over 18,000 nymphs of Anisoptera and Zygoptera, most of which have been identified to species. That is a tremendous amount of data from just one small area.

The larva shown here is a Swamp Darner, Epiaeschna heros. There are 19 records of this species in the ESGR data, and all are from early May to late July. This particular specimen is from sample ESGR-2005.107, on June 15, 2005. It's obviously a last-instar specimen, looking quite ready to emerge at any time. This tells me that E. heros does indeed overwinter as a larva in the Southern Lower Peninsula. I am sure we will get more useful Ode data in the near future from the ESGR collection. The white blobs on the prothorax are water mites.

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