Unusual Behavior? Common Green Darners Ovipositing in Mud

Pair of Common Green Darners Laying Eggs in Mud, September 15, 2021

Nerd Alert: this post is about observing an unexpected, I believe, dragonfly behavior. I find it interesting -- your mileage may vary.

Female common green darners normally lay their eggs in plant stems or floating vegetation below the water's surface. However, multiple times in past years I have observed tandem pairs (the male guarding the female by holding her by the back of her head and flying together to suitable egg-laying locations) laying eggs in dry plant stems or in the dirt or mud where there is no water. I do not know and have not been able to find research into whether or not common green darner eggs laid in this way end up successfully hatching and surviving to adulthood, so I had proposed a research project investigating this question. This year, however, there was standing water in the wetland almost a full month after it was completely gone last year, and once the water was gone in late September, it seemed the common green darners were interested only in migrating south. Nevertheless, on September 15, while there was still water, I observed this behavior multiple times. 

In the photograph above, the tandem pair of common green darners can be seen depositing eggs in the mud two or three feet from the edge of the shrinking wetland pool. My suspicion (or hypothesis if you prefer) is that in this case, their behavior was due to the fact that there was no suitable emergent or floating vegetation remaining in the water itself, as seen in the photo below, taken the same day.

State of the Wetland Pool, September 15, 2021

That said, in other cases I saw pairs ovipositing well away from the remaining standing water (photos below). My observation suggests that this was due to the fact that the shrinking water surface led to a concentrated population of aggressive male common green darners -- I counted at least six flying back and forth over the small body of water above -- intent on cutting in on any tandem pair that showed up. During the ninety minutes or so I was there, I saw instances of a tandem pair being aggressively attacked by a patrolling male, in one case forced to the ground near where I was standing and, I think in at least one case, successfully displacing the original male. I believe, therefore, that the pairs photographed below were resorting to laying their eggs in less contentious spaces further from the water and under cover of more vegetation.  

Whether or not the eggs of any of these three pairs of darners will survive to hatch when the water has returned is still an open question. With permission of the Champaign County Forest Preserves, I had planned to collect plant stems I saw darners laying eggs in once the water was gone, but this year once the water was gone, I did not see any more egg laying. Maybe next year.

Common Green Darners Laying Eggs in Mud, September 15, 2021 perhaps due to intense competition closer to the water

Common Green Darners Laying Eggs in Mud, September 15, 2021 perhaps due to intense competition closer to the water



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