Saturday, January 28, 2017

Species Spotlight: Black Saddlebags

Next up in our Spotlight series is the Black Saddlebags. This species is named for the large black patches ("saddlebags") in its hindwings. You can see the saddlebags in the following photos:

Notice how the saddlebags are confined to the hindwings—the forewings are clear.

What is the purpose of the saddlebags? Well, one purpose in hot climates is to cast a nice shadow for the abdomen to bask in as a way of cooling the body. This is what's going on in the next photo, which was taken in Arizona on a 102˚ F day.

Take a look at the long, thin appendages in the above photo. Perhaps these appendages help with the unique egg-laying process in saddlebag species, in which the male and female detach and then reattach many times in succession.

To be specific, saddlebags lay eggs in a way that is similar to the Apollo lunar landing missions—on those missions the command module remained in orbit while the lunar lander descended to the surface, the astronauts did their exploring, and then the lander returned to orbit to reattach to the command module. In saddlebag species, the male and female hover in tandem over an egg-laying site. When the male is satisfied the coast is clear, and no fish are lurking nearby, he quickly droops his hindwings to signal the female that he is releasing her. She then descends to the water's surface and lays an egg. As she rises from the water the male descends and intercepts her. He then reattaches, and the pair flies off in search of another egg-laying location.

Look for this behavior the next time you see Black Saddlebags while dragonflying. You have to watch carefully, though—the entire process takes only about a second.

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