MOSTLY DRAGONFLIES & DAMSELFLIES, MOSTLY FROM LOUISIANA

Maintained by
Gayle & Jeanell Strickland
Baton Rouge LA

Although we have been involved in nature study and photography for many years, the study of Odonata is a fairly recent endeavor. In July of 2002, a friend showed us a copy of “Stokes Beginner's Guide to Dragonflies” This was the spark that was needed to send us off into the exploration of this fascinating group of creatures. Shortly after acquiring this and other guides, we were led to “Digital Dragonflies” the wonderful Texas A & M website that featured superb images made with a standard flatbed scanner! Out of this grew our passion: To produce color plates of the Odonata encountered here in Louisiana and nearby states. Initially we included a lateral and a dorsal scan of each sex of each species encountered. When we discovered the various color phases within a single species and the variation of color with age, it became clear that several scans of each species would often be needed. These were stored as 400 dpi jpg files. If printed without resizing, life-sized images on a 5 by 5 inch print would be produced. Locality and identification data is printed directly on the plate.

We welcome and appreciate your comments, responses, etc., especially if you think we have made an identification error. Our Email address is noted below.

From time to time we have added features that we hope will make the plates more useful. These features are listed here in approximately the order that they were added:

When we started scanning damselflies, it was immediately evident that life-sized images on a 5 by 5 inch format was not workable. The minuscule image of a tiny Ischnura hastata, (Citrine Forktail) would be useless. Since we believed that it was important to record life-sized images of each specimen for comparison purposes, the solution was to print both life-sized and enlarged images of most damselflies and many small dragonflies on the same canvas. The enlargement factor, which varied from 1.5X to 3.0X was printed near the enlarged image. Smaller specimens were scanned at 1200dpi. This allowed 3X enlargement while maintaining 400dpi resolution.

Acquisition of digital photographic equipment led to the inclusion of an enlarged image of the face of the specimen. We also started our secondary project of digital photography of Odonata mostly in the wild. These photographs are stored in separate albums apart from the plates.

Use of combinations of macro lenses and tele-extenders on a digital SLR permitted the addition of greatly enlarged photos of important details. These are usually various views of the genitalia which are required for identification of a number of Odonata.

As we piled on additional features, the 5 by 5 inch format became very crowded. Realizing that there was nothing sacred about the 5 by 5 format, it was changed to 6.5 inches wide by 5 inches high. This is our current format.

In order to view the plates at highest resolution, after opening the image, click on “get original uploaded image” This will take several seconds (broadband connection), or up to 40 seconds with dial-up. This will provide a 2000 by 2000 pixel image for the 5 by 5 inch plates and a 2000 by 2600 pixel image for the 5 by 6.5 inch plates. Unless your system automatically resizes the image, it will be larger than the monitor screen, but you will be rewarded by extremely fine detail.

Variations in computer monitors and printers can lead to serious distortion of the colors of an image. On our more recent plates a small grey square may be seen in the upper right corner. This is a small piece of a Kodak Neutral Grey Card that was scanned at the same time as the specimen. On your monitor or prints it should appear gray, not pinkish or greenish or otherwise tinted. If the gray is not neutral, colors of the plate will not be displayed correctly. .

(The following is boring unless you actually plan to make measurements)
If you have access to the full edition of Adobe Photoshop, (CS3 is the latest version), accurate measurements may be made on these images using the measuring tool. The measuring tool is not included in Adobe Elements. The full edition is required. Note that measurements made on enlarged images must be divided by the enlargement factor to obtain the correct value. The plates of larger specimens contain only the life-sized image and the directly measured value is correct. We have checked the accuracy of this method and find it to be good to slightly better than plus or minus 0.2 mm. when scanned at 400 dpi. Our enlarged images are scanned at 600 to 1200 dpi (1.5x - 3.0x) and measurements made on these images will exhibit 1.5 to threefold improved accuracy. Accuracy of the method was determined by measuring scanned images of an optical reticule for smaller dimensions, and scanned images of a machinist’s rule for larger dimension. Only the scans (side and top views of the complete insect) are to scale and therefore useful for measurements. The view of the face and enlarged details are not to scale.

Gayle & Jeanell Strickland
Baton Rouge LA
gstrick3atcox.net (substitute “@” for “at”)