The Strange Mating Behavior of Green Darners

September 11, 2013

Nature Notes by Bill Dunson

The Strange Mating Behavior of Green Darners

The Strange Mating Behavior of Green Darners

I imagine most of you have observed dragonflies and damselflies in the so-called “tandem position” in which the male grasps the female with the tip of his abdomen and the two fly around together. I had a good opportunity to photograph a pair of green darners (see photo) doing this today in our pond; this shot actually shows the male in front holding the female while she lays eggs in the water.

Since I am always interested in the concepts behind unusual animal behavior, you will not be surprised when I wonder why this strange arrangement occurs. There is a concise description of the breeding process in dragonflies on pages 16-20 in Giff Beaton’s book “Dragonflies and Damselflies of Georgia and the Southeast” and you may want to read that for a fuller account. The main point is that the male wants to assure his paternity so he cleans out sperm from previous males, deposits his own, and holds onto the female while she lays eggs that now must be fertilized

by his sperm.

This seems to be an amazing behavior by a lowly insect who certainly is not aware of the implications of this activity. Indeed the evolutionary interpretation would be that males who catch a female, mate with her and stay with her to assure that another male does not replace their sperm, have a higher chance of having progeny. So the behavior is selected for and becomes the norm for the species. Other things then come into play, such as competition among males for females and for territory of high quality. And you thought there were just a bunch of bugs flying around a pond!

Nature is incredible in its diversity and detail. The more you know the more amazing it becomes.

Bill Dunson, Englewood, FL & Galax, VA
wdunson@comcast.net

Bill Dunson

About Bill Dunson

Bill Dunson, born in rural Georgia, skipped 12th grade and went directly to Yale. Bill subsequent-ly received a PhD in Zoology from the University of Michigan, studying softshell turtles. Bill is Professor Emeritus of Pennsylvania State University thanks to a career spent entirely at that institution, teaching and doing research on the physio-logical ecology and ecotoxiciology of reptiles, amphibians and fish. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. He has served on many advisory boards here in Southwest Florida to preserve the water that gives life to our region.

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