Sunday, May 29, 2005

Libellula quadrimaculata

dragonfly 169 2855a
Originally uploaded by lorayne.

I didn't shoot this one, but I'm using it as an example of some awesome Odonata images that have been appearing on the group I started on flickr. You can see them here:
dragonflies pool

Tuesday, May 10, 2005

Eastern Forktail

Eastern Forktail
Originally uploaded by argusmaniac.

Ischnura verticalis, also known as the Eastern Forktail, is perhaps the commonest species of Odonata in North America. This little sprightly fellow flew up in front of me near a pond off Embury Road in NW Washtenaw Co., MI. It is one of the earliest species to emerge, and can be found in any pond-like environment, from storm water retention ponds to bakyard lily pools and of course, all of our typical natural ponds and sloughs. It has multiple generations per year, and seems to be abundant just about anywhere. Females are mostly all dark, but the immature adult females may also be orange and black. As they age, the turn a bluish-gray color, and these different manifestations of color patterns confound inexperienced ode watchers/collectors, so that I used to get people sending me various specimens that they thought were three different species. With all the new ode books out there, people are being educated on this topic, so a lot more observers are aware that colors may change through the course of an adult dragonfly's life.
The Eastern Forktail IS a pretty little damselfly, even if it is the Odonata equivalent of an English Sparrow. -- males are pretty, and everywhere, and human influenced landscapes (wetlands) seem to cater to them.

Sunday, May 08, 2005

Spring darner - May 8

Spring darner
Originally uploaded by argusmaniac.

Basiaeschna janata is a resident of streams, so finding one this early is a bit unusual. As you can tell, it's a female that is not sexually mature, as the coloration is rather pale. She probably emerged from the larval stage within the past 48 hrs. This particular one was flying in an open field area near Sullivan Lake, in NW Washtenaw Co. Our total sights for the day were 2 Anax junius, several Ischnura verticalis, one Ischnura posita, Basiaeschna janata, and many recently-emerged Enallagma boreale (at Green Lake, N of Chelsea). It was a beautiful early may day, with temps around 74°F, and mostly sunny. Even if I had not seen a single odonate, it would have been a good afternoon. Seeing my first odes of the year made it an even better one.

05/10 -- Carl Freeman brought up an observation that he has seen B. janata around lakes, too. That is true -- a lake with enough wave action can also harbor a population of this species, and the larvae may also be living at the mouth of the lake if there is a stream exiting or entering. For the most part though, this is a lotic species.

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...