Tuesday, September 18, 2007

Waning Days of Summer

Lestes sp. at Lillie Park, Washtenaw Co., MI

It's mid-September, and though we had a very hot August and early September, the weather is obviously cooling down, and the days are noticeably shorter form the great long days of June. Whereas it was easy to find a dozen or more dragonfly species at a time in June, by September, the fauna has become less diverse. It's time for the gliders and wanderers and the common green darners here.

I was out at Lillie Park in Pittsfield Twp. yesterday on a beautiful September day. Sunny and maybe a high of 70 or so. I haven't been there for quite a while, and since it is only a few miles from my house, I should visit there more often. Yesterday, I saw a number of Pantala flavescens, an Anax junius, a single Tramea lacerata, a few Sympetrum vicinum, numerous Lestes sp., and Argia fumipennis violacea. I didn't bring a net with me, and because of that, the Pantalas were flying almost at arm's length in front of my face as they fed on gnats. It was fun to watch their seemingly effortless ability to hover and eat. Likewise, the lone green darner was flying quite close to me. I didn't need to collect them, as I know the species that are out this time of year, and yeah, I hate identifying Lestes.

argia fumipennis

Argia fumipennis violacea.

So long as we have warmer weather, we'll still see some late-season action. Hetaerina americana and H. titia ought to still be on some of the rivers, as well as Aeshna umbrosa and Boyeria vinosa. In fact, I saw an Aeshna umbrosa in my front yard on Sunday. There may also be some Stylurus species along the Huron as well. Years earlier, I collected a lot of Aeshna species along Lake Michigan in Emmet Co. as late as mid-October. So, yes, the season is coming to a close, but it can still hold some surprises for us.

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