Tuesday, May 03, 2005

WTF? It's May 3, and and I see SNOWFLAKES!!

What wacky weather we have. Almost a month ago, it was in the 60s. We lost all our glaciers (at least in the Lower peninsula -- you yoopers, probably still have them). Then it climbed to near 80. Students were sunbathing in thongs on campus. Bees were flying. Anax junius was spotted. Daffodils and Magnolias were blooming like crazy. Then, two weekends ago we had 4 inches of snow. Thankfully, it left quickly. The temperatures, however, have remained cool, and haave not ventured above 55 for the past week. Today, it is cold and gloomy, and I see snowflakes coming down. Not enough to do anything but make me wonder weher our spring has gone.
Well, what does all this mean for Odonates? Those species that live here year-round, and are currently in the larval state, hunkered down until the day they will release themselves for an aerial life. That all depend on degree-days, something which has been well-established for many flowering plants and economically-important insects. There have not been any such studies for Odonata, but I think one could do it by watching the phenology of some of the flowering trees and the date on which certain dragonflies/damselflies emerge. I have seen massive emergences of Enallagma boreale around the 10 May, and likewise, Steve Ross has photographed big emergences of Epitheca in Mecosta County, where it looked almost like a cicada hatch. How these events are influenced by weather is something that we need better records of, and that is a great project for someone to do long-term if one lives near a small pond.
Simply start recording the maximum daily temperature of the water and the air as soon as the ice is off, and then record the emergence dates (first record and then a dialy average) of the Odonates. Do that for 10 years, and voila! At least one set of parameters for one pond somewhere in Michigan...

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