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Damselfly Thoracic Patterns

This thorax shows most of the markings commonly used in ID - a middorsal line (blue), the middorsal stripe (black), then the antehumeral stripe (blue) and the humeral stripe (black)

While the size and color of the markings may vary, the pattern of the top of the thorax is quite consistent throughout all damsels, especially Pond Damsels and Spreadwings.  Look at the illustration to the left to see the typical stripes found on most damselflies.

Many damsels do not show the mid-dorsal line shown by this Big Bluet, or at most it is a thin line.  Generally the black line down the center of the thorax is called the middorsal stripe; this is followed by a colored stripe called the antehumeral and a black stripe called the humeral stripe.

Generally the side of the thorax is the same base color as the rest of the damsel, although it may fade to whitish or in a very few cases may show a contrasting patch of color.

Pay special attention to the relative width of these stripes, any contrasting colors or any iridescence.

Some species have the markings reduced to thin lines or lacking completely

Many species, especially females, show a broad black middorsal stripe

Bronzy or metallic coloration is significant, especially in spreadwings

Helpful Hints:
In identifying both the Spreadwing and Pond Damsel families, the relative width of the antehumeral or "shoulder" stripes is important for identification.

© 2020 Sheryl Chacon Search