The Guy Who Fell In Love With Midges

Tiny Things Can Tell Big Stories

Posted on: March 31st, 2021

Sheltering-in-Place Blog Entry #43

I began collecting Chironomidae pupal exuviae (the skins of the pupae left floating in the water after the adults emerge) in Costa Rica in the 80s, and in Venezuela long before that.

Well, it probably won’t get much weirder than this blog entry. However, in my defense, there are a few hundred people around the world (OK, maybe about 100…or perhaps fewer…) who can relate closely to this story and may even experience a  small (really small) bout of nostalgia. If you’re not one of those people,  perhaps my tale can give you some insight into the deep, nerdy hearts and minds that run through the community of field biologists/entomologists. And, hopefully, you’ll get a sense of how little things in nature are connected to the bigger things that make the world such a special place.

In Venezuela, where I was born and raised, we have an expression to qualify and build acceptance of the weirdness of other people’s passions. “Cada loco con su tema,” we say, loosely translated as “every crazy person with their song.” What I’ll share today is my crazy song.

It all started in 1976. I had just transferred from three long years in mechanical engineering to the biology department and a career that I had been waiting to launch at my university, finally. There were about a dozen or so students in this first cohort, most of them transfers from other majors including chemistry, architecture, and engineering, plus a handful of new students fresh out of high school slightly concerned about all those “old” classmates who seemed at ease with the novelty of university life. Most of our professors, all new to the university, were hardly older than the oldest students and equally enthusiastic about developing exciting courses in the new curriculum, and eager to take students to the field for research expeditions and course projects. That first year, I spent all of my time between a full-load of scheduled classes and preparing lab activities for my classmates. Being the first student group in the new cohort, some of us were chosen by our professors to be teaching assistants to our classmates. But the best part for me was working in any capacity in my professors’ laboratories. A complete immersion into biology was a dream come true. I assisted with projects including how plants adapt to cold environments, genetics and evolution of spiny rats, microscopy of fish gonads, genetics and natural selection of drosophila flies, and more while going to remote areas of the country in actual expeditions by land and water.

Bill Coffman sampling midges in Costa Rica.

But the last laboratory I joined that summer was the aquatic ecology lab, with my professor Dr. Roger Carrillo. Our main work was to explore and sample populations of aquatic invertebrates in a broad range of freshwater ecosystems, including forest streams and rivers, lakes in alpine and lowland areas, and springs. That’s where I first encountered midges. In every sample I collected and examined, between half to almost 90% of the organisms collected were larvae of non-biting midges, a group of mosquito-like flies known as the family Chironomidae. Related to mosquitos, craneflies, and other Diptera, chironomids were the most abundant insect larvae and the most diverse in sizes, colors, and shapes. With no keys or guides for their identification, I soon became deeply frustrated in my attempts to tell species apart. They all looked similar in general shape, and while they have unique characteristics, I could not get further down in the taxonomic scale beyond the subfamily.

A “soup” of debris and midge larvae. Within, many larvae squirm and hide.

That was the moment when Roger’s Ph.D. professor, Dr. Bill Coffman, from the University of Pittsburgh, came to visit our newly formed department. Bill was one of the few world experts in chironomids, gave a lecture — in English, which most of us could barely understand — and came to the lab to spend some time with our collection. I took that first opportunity to show him a petri dish filled with the larvae from one of my sampling sites. Bill sat at the microscope with my sample and quickly made three small larvae piles with my tweezers. Aided by Roger’s translation, Bill excitedly explained:

This little group here are probably new species. I can recognize the genera but can’t take them down to species.” 

I was already transfixed.

This other group,” he continued, “are very different and unique and are probably new genera still undescribed and named.” 

After listening to the translation, my eyes grew bigger.

And this few,” he continued, his voice ringing with excitement, “is probably a new subfamily! They are so strange and novel that I can’t place them at all!

This was one of those watershed moments in my life, an epiphany that set my career direction for many years to come. I wanted to be able to do exactly what he had just done. I wanted to be able to advance discovery by looking at a collection of insects and knowing what was known and what was new to science by drawing on accumulated knowledge from experience and connections with other scientists. From that day on, my future was etched in my brain as if on stone. I would go to the University of Pittsburgh to pursue my Ph.D. (I hadn’t even finished my undergraduate work!) and become an expert on this group, just like Bill. 

Collecting midges starts in the field. Live samples are taken to the lab and each larva is placed into individual vials to complete its metamorphosis. Larvae turn into pupae and then the adults emerge, becoming an “association” where the larval and pupal skins accompany the adult.
Once, I dipped my hand into the scalding water of a hot spring in Costa Rica. My hand emerged covered in larvae of a species that thrive in heat and low oxygen conditions that few other creatures can survive.

You may wonder  ‘What’s so cool and exciting about these tiny insects that scientists have dedicated their entire careers and life’s work to researching them?” Well, to start, they are incredibly diverse, with tens of thousands of species in all types of freshwater, terrestrial, and even marine habitats. The great majority of the species, especially in poorly researched areas of the world like tropical forests, are still unknown and undescribed or named. They represent at least 50% or more of the species and insect biomass in aquatic ecosystems. Fish, birds, and other insects, some exclusively, feed on larvae or adults, which form a broad and essential base to food webs. These insects are indicators of water quality too. They have incredible adaptations that allow them to survive and even thrive under the most stressful environmental conditions, such as the scalding waters of hot springs, oxygen-poor sewage ditches, and heavily polluted waters. And incredibly enough, their evolution, species diversity, and world distribution have been instrumental in elucidating the sequence of separation of all major continents from the original landmass known as Pangea. The lowly, tiny, excruciatingly difficult to work with but fascinating midges are rock stars in aquatic ecosystems.

This specimen of non-biting midge from the Dominican Republic was caught in amber  more than 5 million years ago. It looks just like its modern counterparts.
Fossil midge exuviae.

It would take many pages to describe the journey I started so many years ago, including collecting expeditions in over 200 streams, rivers, springs, lakes, tree holes, epiphytes, and even carnivorous plants where midges have adapted to live their lives. Some of those stories can be found in the FURTHER READING links below. But the moral of the story is a simpler and deeper one. I chose midges as the subject of my research life because I first fell in love with their diversity and unique adaptations. I felt challenged by the difficulties of working on a poorly known group of tiny insects. Still, as I delved deeper into their lives, I became aware and passionate about the bigger picture that they illustrated.

Tropical rivers and streams are beautiful and very rich in species. Many of them are threatened by human activities, such as pollution, channelization, sand and rock extraction, and deforestation.

Our global biodiversity is still poorly known. There are many estimates of the number of species of plants, animals, and other life forms (a subject for an essay in its own right); the latest and most conservative estimate is about 8.7 million species. Of these, less than 25% have been studied and described (named). At the current rate of habitat conversion (read destruction), pollution of freshwater and marine ecosystems, and clearcutting of forests with all of their incredible flora and fauna, most of these unknown species are likely to disappear from the planet before we even know they exist. This is an irreplaceable loss for the world and for humanity, akin to burning a library of millions of original manuscripts before anyone had a chance to read them and learn from them. Considering that many medical advances (to name one benefit of biodiversity) have come from our study of plants, animals, and microbes, how many medicines and cures for current and future illnesses are we going to miss?

Midges don’t bite humans, nor do they transmit diseases, eat crops, or negatively impact our lives. But they are an integral and essential part of healthy ecosystems, and their loss means the loss of other species tied through food webs to them. I chose midges to study because they are unique, interesting, and even beautiful. They are also instrumental in measuring our impact on our aquatic ecosystems. Knowing them has allowed me to repurpose my passion from the thrill of discovering new species towards the conservation of their habitats and, by extension, the preservation of whole ecosystems, wildlife included.

My version of an MMM (Masked Midge Man), a celebration of the life cycle of a non-biting midge.

I still love to photograph, study, and share what I know about this incredible group of insects. Hopefully, someday, I will figure out how to collaborate with other scientists in describing most of the 500 unnamed species in my collection (together with the collections from Bill Coffman) that now reside at the University of Costa Rica. These collaborations will be essential to obtain funding to describe and share the knowledge with the world. But most of all, I love midges because they were my gateway to becoming a passionate conservationist and working in the noble and essential field of protecting the incredible richness of life. 

 

Carlos de la Rosa
Executive Director

FURTHER READING

How many species on Earth?

Dr. William P. Coffman: Celebrating 50 Years of Research on Chironomidae

Chironomids: a personal journey

  • Hi, Linda! Thank you for your comment. Absolutely, they are very charismatic (to me, at least) and the term would be appropriate. They show extraordinary adaptations to a wide variety of habitats and environmental conditions. And they support a wide range of food webs and species that depend on them. A close relative of the chironomids (family Chironomidae), the genus Chaoborus (family Chaoboridae) from the Great Lakes region of Africa is used as food for humans! They emerge from the lakes in humongous numbers and the locals collect the adults and make small protein-rich patties called “kungu cakes” that they fry and consume. See here: https://link.springer.com/referenceworkentry/10.1007%2F978-1-4020-6359-6_4614
    Carlos

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