Cases of predation by Anax imperator (Emperor Dragonfly) on Zygoptera or Anisoptera are regularly reported. A few years ago, I observed a male Anax imperator capturing an Orthetrum albistylum, but it managed to escape. This will not be the case for this female Cordulia aenea (Downy emerald).
This May 20, 2025, at the very beginning of the afternoon, the weather is very nice with a little wind, and I am prospecting in a part where the heather is low and not very abundant in the Pinail Nature Reserve (France-86). It is 2:24 p.m. and I am overflown, quite noisily, by a large odonate, which I do not identify instantly, but I suppose that it is a mating in flight. I follow it with my eyes and luckily, it lands about fifteen meters from me, in the gorse. Eyes fixed on its location, I hurry towards it, crossing the gorse and depressions in a straight line; those who know the Pinail know what this means!
And I discover that far from mating, one of the odonates serves as a meal for the other; a female Anax imperator is just beginning its meal of a female
Cordulia aenea.
Photo opposite at 14:25:10, 05/20/2025.
Anax imperator is one of the largest odonates in Europe, measuring 66 to 84 mm, while Cordulia aenea only reaches 47 to 55 mm.
I don’t know if the capture took place on the ground or more likely in flight; there is room for doubt, as we see a string of eggs hanging from the victim. Was she laying eggs, or is it simply stress that triggers this reflex laying that also occurs when we humans capture certain females?
As in most cases, predation begins with the eyes, that is, the head, probably to destroy the main nerve centers that could still trigger defense and escape mechanisms. Note that one minute after the start of predation, the head has already been devoured.
The meal continues through the thorax, and the predator is really very busy, which allows me to get closer and closer…
In the photo on the right, we can see one of the mouthparts, a black maxillary palp with 2 terminal claws, just in front of the labrum (which can be likened to the upper lip).
The size of the mouth is spectacular; I had already thought about this when observing a
Cordulegaster bidentata devouring a hymenoptera, years ago, in Ardèche.
Obviously, my persistence got the better of the Empress’s patience, and she took off. I followed her, found her, and took the photo below, but she almost immediately took off again with her prey, and I lost sight of her.
It should be noted that this was the first Cordulia aenea I had seen on the site, even though I had been prospecting all morning; I would see a few more later, but at a good distance from this part of the reserve.
On the Odonates of the World of Insects forum, there is a section Predation between Odonates in which we find several cases of predation by Anax imperator on:
– Gomphus pulchellus
– Sympetrum sanguineum
– Diplacodes lefebrvii
– Libellula fulva
– Crocothemis erythraea
– Orthetrum cancellatum
On iNaturalist, by filtering the Anax imperator in the data of the Odonata project – predation (eating) we have access to these few data (the prey are not always identified).