Fearsome Flies: Meet the Scientist Studying the Top Predators in the Insect World

Flies come in an astonishing variety— some tiny enough to balance on the tip of a pencil, others larger than the palm of your hand.  From shimmering metallic blues to earthy browns, their diverse colors and bizarre shapes are proof that these overlooked insects are anything but boring. 

For research entomologist Torsten Dikow, the curator of Diptera at the National Museum of Natural History (NMNH), the study of flies is teeming with potential discovery.  Throughout his career, Dikow has described 81 new species and published several research papers helping to untangle the branches of the fly tree of life. 

Specializing in three families of Asiloid flies—Apioceridae, Mydidae, and Asilidae (or assassin flies)—Dikow has travelled around the world to conduct field work in tropical rainforests and arid deserts and add specimens to the Smithsonian’s National Insect Collection.  As an open data ambassador for the Global Biodiversity Information Facility and Editor-in-Chief of the open-access biodiversity journal ZooKeys, Dikow has also centered his career on making insect science and natural history collections accessible to everyone. 

NMNH houses the largest collection of flies in the world, and Dikow is dedicated to preserving and expanding access to this scientific cornucopia. “We have something special here at the Smithsonian,” Dikow said. “My goal is to share our specimens so that an entire global community of researchers can use this knowledge to make bigger predictions about the world around us.”

How did you first become interested in entomology as a career?

Insects are amazing because anybody can study them.  Kids and young researchers can go to a park and catch flies, beetles and crickets to create their own little collections at home. Entomology is approachable in that way, and you don’t need to be at a museum or a university to follow your interest in these species.  

I grew up in Germany, and I remember compiling all of these little collections right from my own backyard. I had a few friends that were part of the local entomology club where I grew up.  They invited me on field trips where I became fascinated by all of the different sizes, shapes and colors that insects represent.     

I think all of us entomologists enjoy organizing things, and I definitely had that interest when I was young.  I would organize my collections to get to know local insect species, and I now realize it was just a much simpler version of what I do every day at NMNH.  There is something for everyone in the insect world, and there are countless questions that still need to be answered.

How did you decide to specialize in the study of assassin flies, and what do you find interesting about this group of insects? 

As an undergraduate student in Germany, I wanted to study abroad to see more biodiverse areas of the world. I had the opportunity to travel to South Africa and work at the KwaZulu-Natal Museum, which houses the largest fly collection in Africa. The director of the museum was Africa’s foremost expert on assassin flies, and I spent every free hour in the museum collections.  

The interesting thing about assassin flies is that they are expert predators in the insect world.  They kill other insects for breakfast, lunch and dinner, snatching them right out of the air as they are flying.  They are capable of overpowering prey like beetles, wasps and honeybees that are the same size or even larger than they are.  

But a tricky problem for assassin flies is that they only have piercing-sucking mouthparts.  They can’t chew.  Instead, they have to inject their prey with venom that liquifies their insides so that they can suck out the juices.  

But finding this predatory niche has actually aided assassin fly evolution. They have been able to diversify, and there are over 7,500 species in this family today.  To put that in context, there are only around 6,000 mammal species known to science.  So, this is a huge number of species for one insect family, and there are many more to be discovered.

You have done lots of your fly collecting fieldwork in desert habitats.  How do you find these tiny insects in vast and arid landscapes? 

I find deserts fascinating for many reasons, and they are actually perfect for catching flies. In a habitat like a tropical rainforest, these miniscule insects could be anywhere.  They could be sitting above me, hiding in the shadows, or resting deep in the thick shade of the forest.  But deserts are two dimensional, and there is not much vegetation to deal with.  Everything is wide open for discovery. 

After many years in the field, I have a pretty good idea of where flies might be found. Assassin flies like to sit on rocks, leaves and even dunes of sand.  In a desert habitat, there are relatively few of these perches for them to choose from. So, as we walk through the environment, we scan the ground for perfect perch locations where our flies might be found.

One of the first things that tells me a large assassin fly might be nearby is the distinctive buzzing noise they make as they zip past.  Then, I’ll follow the sound and get closer and closer until I finally see the insect I am after. These insects are fast flyers, and you have to be quick if you want to catch them.  I have a high-quality aluminum net, and I slam it down onto the sand before the fly can get away.  It can be hard work, and I do miss my targets sometimes, but it is also a lot of fun. 

What is your favorite part about being an entomologist?

My favorite part of being an entomologist is discovering new species.  I have scientifically described 81 new species throughout my career so far, and I hope to add many more to that list.  When I earned my master's degree more than 20 years ago, I was mainly describing museum specimens that had already been collected by other researchers.  Now, I am able to travel all over the world to remote locations in Africa, Southeast Asia and the Southwestern U.S. and collect new species right from the field.   

One of my current research projects involves traveling to the same remote locations in the Namib Desert of Namibia at different times of the year.  An assassin fly is active as an adult for only two to three weeks out of the entire year, and these short windows are different for every species.  By re-visiting the same locations during different seasons, I am more likely to catch species that I have never encountered before.

This October I will be heading back to Namibia for a few weeks of field work, and I am hopeful that I will discover at least one new species.  Very few people have ever been to these locations in October, so there is a whole new opportunity for discovery.  There is nothing quite like the moment in the field when you realize you have just collected something entirely new to science. It's amazing. Then, bringing that discovery back to the Smithsonian to add to the national collection, knowing it will be studied by generations of future scientists — it is truly special. 

As a curator, you are passionate about making biodiversity collections open and accessible. Why is it important to share NMNH’s specimens with the world?

Here at the Smithsonian, I am lucky enough to help curate the largest collection of flies in the world.  And all of our 3 million specimens have data attached to them. We know where they were collected, what species they are, and how they fit into the evolutionary tree of life.  All this data is available to me and the other entomologists at NMNH, but not every researcher from around the world can travel here to use the collections in person.   

Taking that information and putting it into an openly accessible database will offer a huge benefit to the scientific community. We can build upon each other’s research and use taxonomic classifications from all over the world to make large-scale climate and environmental predictions.

"There is something for everyone in the insect world, and there are countless questions that still need to be answered." — Torsten Dikow, NMNH research entomologist and curator

For example, aquatic insects like stoneflies and caddisflies are important in the water quality assessments of streams, lakes and ponds.  But going to a stream and collecting a snapshot of the insects living there will only give you a tiny piece of the picture. If a researcher can compare their data with decades of research conducted by other scientists, they can trace how water quality is changing across space and time. 

At the end of my career, I want to be able to push one button that will bring up every piece of scientific data I have ever collected. I want entomology to be a connected space, where any scientist in the future will be able to find my research and pick up where I left off. 

This interview has been edited for length and clarity.  

Meet a SI-entist: The Smithsonian is so much more than its world-renowned exhibits and artifacts. It is a hub of scientific exploration for hundreds of researchers from around the world. Once a month, we’ll introduce you to a Smithsonian Institution scientist (or SI-entist) and the fascinating work they do behind the scenes at the National Museum of Natural History.

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Emma Saaty | READ MORE

Emma Saaty is a Science Communications Specialist at the Smithsonian National Museum of Natural History.  She brings science to the public by covering natural history research for Smithsonian Magazine's, Smithsonian Voices.  Additionally, she tracks media coverage and coordinates filming activities for the museum’s Office of Communications and Public Affairs.  Emma recently completed her Bachelor of Science in Biological Anthropology with a minor in Journalism at George Washington University where she conducted research on Virunga mountain gorillas with GW’s Life History and Skeletal Biology laboratory.  You can find her here.