Friday, July 8, 2011

Dragonflies

Summer is the time of dragonflies and their numbers have been increasing steadily for the past couple of weeks. The only permanent body of water at Blue Jay Barrens is the water garden outside the front door of the house. The brick is a good anchor for nymphs ready to make the transition to adult form.


The newly emerged adults use their shed skin as an anchor upon which they hold while allowing their wings to expand and their exoskeleton to harden enough to allow flight. This is a very precarious time for the adult. A fall could cause damage that would make flight impossible for the dragonfly and result in its death. It’s a marvel that any of them survive this critical period.


Most make it to the flying adult stage and manage to spread themselves widely across the landscape. Fortunately for me, dragonflies will hunt far from water. Otherwise I would have few opportunities to observe them. I’m seeing many of these female Common Whitetails.


I’m not seeing the variety of species that I’ve seen in the past, but there’s still a lot of summer left. The Calico Pennant is an attractive species. This is a female.


Widow Skimmers are the most common species found in my fields. This is a female.


Many species of dragonflies exhibit sexual dimorphism, meaning the males, like this Widow Skimmer, have a different coloration or pattern than the females. I tend to find far more females than I do males. I once thought that this was due to the male’s habit of defending breeding territories near suitable water bodies. This may indeed reduce the number of males you find in the fields, but then I learned that there was another reason I was seeing so many females.


Adult dragonflies do not emerge with their full coloration. It takes several days for the color to develop and the pattern to settle into its final form. During this development stage, males pass through a phase when they resemble females, so a casual observation would give you a count with females outnumbering the males. That can cause some confusion for the beginning dragonfly enthusiast. I’m thinking this is a young male Widow Skimmer. It looks an awful lot like that female.

2 comments:

  1. What perfectly wonderful images. The wing shots are terrific.

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  2. Thanks, Lois. I think dragonflies are shaped and colored to be the perfect photographic subjects.

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