Helicopter Damselfly (Mecistogaster ornata), perched on a nearby grass and about to fly away, Cuernavaca (Morelos), Mexico. Photo by Catalina M. Suárez Tovar, 2020.
December Species of the Month: Ornate helicopter damselfly (Mecistogaster ornata)
The December DSA “Species of the Month'' is the Ornate Helicopter Damselfly (Mecistogaster ornata), a species belonging to the subfamily Pseudostigmatinae (Zygoptera: Coenagrionidae). This subfamily is morphologically characterized by their long abdomen and the absence of pterostigma, or its modification into a false multiple-cell pterostigma. It encompasses some of the largest damselfly species, with an average total length of 87 mm (almost three and a half inches). Its distribution ranges from Mexico, through Central America, and extends across a significant portion of South America, reaching Brazil and Argentina. Read on to enjoy the story of how Colombian biologist Catalina M. Suárez Tovar and master’s degree student Iván Sandoval García encountered this intriguing species.
The Quest for the Helicopter Damselfly
Mecistogaster ornata Rambur, 1842 the lemon-tipped helicopter or ornate helicopter.
“…it is the hesitation that grants it its charm, resolution or distress take away any grace.”
—Byung-Chul Han
It was December 2019 and we were sampling central Mexico’s state of Morelos. In order to study Odonata communities and their changes in an urbanization gradient, we were looking for adult Odonates in rivers and streams of different localities. In each site, we conducted a comprehensive characterization of vegetation, measured various physico-chemical properties of the water, and reported on characteristics of the urban environment. Subsequently, we documented the species of dragonflies and damselflies, along with the abundance of each species.
One of the places visited is located in Temixco (Morelos). Near a highway with a large traffic flow, we found a site with shrubs, trees, and herbaceous vegetation. The river was quite deteriorated due to garbage and waste discharge from nearby homes. There were even pieces of cloth on the trunks of the trees, several meters high, which during the rainy season were carried away by the current. Despite the contamination present in this site, during our sampling we were able to observe many individuals of the genera Hetaerina, Argia, Archilestes, Apanisagrion and Macrothemis. They took advantage of the remnants of aquatic and herbaceous vegetation, as well as some rocks, to perch and take in the sun rays that the tallest trees allowed to pass through.
The location where the authors first saw the Helicopter Damselfly (Mecistogaster ornata) in 2019, Temixco (Morelos), México. Photo by Catalina M. Suárez Tovar, 2019.
An Unexpected Encounter
Iván's story: Among the 19 locations we visited for the project, it was in this very disturbed site where something unexpected happened. We were about to leave the site. I was looking around in search of more Odonates when I saw a damselfly descending from the nearest tree. The beating of its wings was hypnotic and erratic. It flew slowly, and its wings seemed to be shining because of the angle of the sunlight. It went down until it stopped a meter off the ground and a few centimeters from me. It took me a moment to react. I tried to catch it with my net, but a bush was in the way. The damselfly slowly rose to the top of the same tree, with what seemed to me to be a carefree and indifferent flight towards my attempt to capture it. I had never seen this species! What was it? I was surprised that I couldn't catch it despite its slow flight.
Cata’s story: Ivan told me at the end of the workday that he had seen an unusual damselfly. He said, “It was a large damselfly. Each wing was about six cm long. It flew slowly and had yellow tips on its wings. It seemed to hypnotize me. When I tried to catch it with my net, it was already very high and I couldn't reach it anymore.” I immediately remembered the species records that we had reviewed before going out into the field and I told him: Mecistogaster ornata! I looked for some photos of the species, and when I showed it to him, he confirmed it.
Helicopter Damselfly (Mecistogaster ornata), perched on a nearby grass and about to fly away, Cuernavaca (Morelos), México. Photo copyright Catalina M. Suárez Tovar.
These damselflies are typically found in the canopy, where prey such as spiders are abundant. They lay their eggs in accumulated water in tree trunks and inside bromeliad leaves. Such water-filled plant cavities are known as phytotelmata. M. ornata is characterized by yellow spots at the tips of its wings, with a white stripe that outlines the spot, distinguishing it from the rest of the wing. Its flight is relatively slow, with each wing moving independently, resembling the rotation of a helicopter's blades.
It had only come down from the canopy to visit us briefly, but it didn't get close enough to photograph it. From that moment on, the entire work group was attentive to the canopy at the sampling points that we visited in the following days. But we didn't find it again.
The Reunion
One year later, we visited the same locations to conduct samplings as in the previous year. This time we traveled with the precautions and restrictions derived from the Covid-19 pandemic. The city's roads and streets were almost empty, but the amount of waste in rivers and streams surrounded by homes was considerably higher than the previous year. The working group was a little larger than the year before.
Expedition group on their quest for the Helicopter Damselfly (Mecistogaster ornata), Cuernavaca, Morelos, Mexico. Photo taken with Catalina M. Suárez Tovar’s camera, 2020.
Why? Apart from this project, we were taking data for two more projects: one that evaluated the incidence of parasites in Zygopterans and another that sought to quantify color changes of Argia spp. that we found in the urbanization gradient that we had defined.
We shared the experience of the previous year with the new members of the group. We also placed special emphasis on Mecistogaster, almost like a “Wanted!” advertisement. In this way we were all doing our work in the field, but we paid close attention to the canopy in order to identify the distinctive traits of the described species.
We returned to the place where we had observed it the previous year, excited by the idea of finding it there again. Although we extended the sampling time in that place, we did not find it.
We continued our journey to a park within a residential area in Cuernavaca, Morelos, which was one of the last sampling places of the year.
Second expedition site in Cuernavaca, (Morelos), México, where the team would find the Helicopter Damselfly (Mecistogaster ornata). Photo by Catalina M. Suárez Tovar, 2020.
Although the river was surrounded by a large number of trees and herbaceous vegetation, we recorded the presence of waste coming from homes in different parts of the river. We divided up to make observations on different transects. Suddenly we heard a shout! Our friend Xavi saw it flying. He immediately caught it! We all stopped our observations and ran to him, where we could closely observe and photograph M. ornata.
Iván with the Helicopter Damselfly (Mecistogaster ornata) individual, Cuernavaca, Morelos, México. Photo by Catalina M. Suárez Tovar, 2020.
It was a female who seemed calm despite being the focus of attention of seven humans who observed and photographed her at the same time. After a brief talk about the natural history of this species, including a discussion of the oddity of discovering a species typical of tropical forests in two of the most urbanized locations on our tour, we let it fly away.
Cata Suárez with the Helicopter Damselfly (Mecistogaster ornata), Cuernavaca, Morelos, México. Photo by Ulises Castillo Pérez, 2020.
First, she perched on some tall grasses near the spot where we were gathered to observe her. Then, she continued her wandering flight. A few meters later, she encountered another member of her species. From afar, we saw the yellow spots on its wings appear and disappear above the tallest trees.
We were all in awe of our close encounter with this giant damselfly.
Catalina M. Suárez Tovar is a Colombian biologist passionate about the study of dragonflies and science communication. She does her postgraduate studies in Mexico, where she studies topics related to the evolutionary ecology and conservation of this beautiful group of insects. She is currently finishing her doctoral project where she studied the impact of urbanization on dragonfly and damselfly communities and identified the adaptations of some species to urban environments.
Iván Sandoval García is a master´s degree student specializing in the interactions between beetles and millipedes and their symbionts or parasites. Although he is not an expert in Odonata, fieldwork involving them is his favorite because he finds everything about them astonishing.
