Follow-up to my last post, “It’s a Bug Eat Bug World”
Umpqua National Forest, Oregon: Aug 21, 2010
Sedge sprites in a copulation wheel. The male holds onto the back of the female’s head while she retrieves sperm from where he has deposited it in his thorax.
I’ve been feeling a little chagrined that I must have had sedge sprites within inches of my feet many times during the past five years, and yet I never saw one. Today we are back at the pond where we found them two days ago. I just found some right where Dale often sat on his stool in years past. In fact he spent an hour or two within a few feet of them today. He had opportunity too!
Sedge sprites were first found in Oregon in 2001. They are so tiny I almost have to imagine they exist. Now that we’ve found them, I know why they escaped our attention. They are only an inch long and their abdomen is about as big around as my darning needle. When they take off and fly, it is almost like popping a bubble – they disappear. Most damselflies are a little bigger and easiest to spot in flight. Their bright colors give them away.
Sedge sprite colors are exquisite, but get lost in the sedges. They have oversized turquoise eyes, metallic emerald on top of their thorax, a dark abdomen and more turquoise on the sides of their thorax and the tip of their abdomen. The females we are seeing look very much like the males.
Odonata (dragonflies and damselflies)sex is a little odd. First the male deposits his sperm into a pocket on the underside of his thorax. Then he searches out a female and grabs her behind her head. The anatomy of different species varies enough so that the male’s appendages on the end of his abdomen only fit behind the head of the female of his species. Often the pair fly about ‘in tandem,’ i.e. basically in a straight line with the male hanging onto the female. Eventually the female brings the tip of her abdomen around and gathers the sperm out of his pocket on the underside of his thorax. Many species are perched when they go into this copulation wheel, but others do it in the air. They can navigate reasonably well even when in a copulation wheel. After transferring sperms some species break apart and the female goes off to lay her eggs. The sedge sprites we watched were perched during their copulation wheel and stayed in tandem during egg laying. While she busily deposited eggs either into or onto some barely submerged sedge, he maintained his hold on the back of her head.
Still attached the male hold this funny stiff position while the female lays her eggs on some soggy sedges floating just beneath the surface of the water.