OCT 14, 2021 9:00 AM PDT

The Physics of Insect Swarms

WRITTEN BY: Hannah Daniel

Do you know those pesky bugs that happen swarm in front of your door right as you open it? Those swarms— and the insects that make them up— maybe less random than you think.

Above Video: Swarms of midges move in mesmerizing patterns. If you’ve never seen one, you can watch a short clip of a massive swarm in Myvatn, Iceland.

Swarms of insects such as midges are not random, and mathematicians have been able to find patterns in the swirling masses. Observed swarms behave like liquids, almost shifting in and out of ways in the blink of an eye. Like birds in a flock, it makes sense that these midges could also share some collective instinct about their flying patterns. 

Some researchers have compared the swarming midges’ behavior to the property of criticality. In this instance, criticality means the ability to instantly respond to a stimulus no matter the direction or intensity it comes from.

The midges fly in a way that allows them the maximum number to respond— if a predator attacks from one side or there’s a stimulus on the other, the midges can adapt quickly. They have been compared to magnets in this way. Right before magnetization, all of the particles in a magnet suddenly shift orientation, as if they were prepared for any type of magnetic response without knowing what that response would be.

While particles don’t exhibit cognition as insects do, there may also be other reasons that swarms are not perfect examples of criticality. True criticality can only be achieved with more units per system than there are midges in a swarm. Also, it might not be physiologically possible.

Dr. Miguel Muñoz of the University of Granada, Spain, explained that if the swarms were to reach true criticality, then the swarm would be responsive to every single stimulus and that’s not evolutionarily advantageous. The swarm doesn’t react to every change in the wind or speck of dust that drifts by— if they did, they would never be able to do anything because they would be in a state of constant stimulation and response.

So, while midge might exhibit some of the characteristics of criticality, it’s not likely they are experiencing true criticality.

In different environments, the swarms will respond different ways. Sometimes they act like solids, splitting in two when pressured, and sometimes they act like liquids, bending around our hands when we reach out to swat them away. Sometimes, they act like swarms of birds dancing in the sky.

Research on swarm dynamics might tell us more, but maybe it’s more important to focus on the individual insects, not the collective. Perhaps, swarms can exist in all of these forms because of the minds of all of the individual insects.

Only time (and further research) will tell.

Sources: New York Times, IOP Science

About the Author
  • Hannah Daniel (she/they) is a recent graduate of Carnegie Mellon University, where she received a Bachelor of Science in Biology with an additional minor in Creative Writing. She is currently located in the Washington D.C. area pursuing freelance writing opportunities and full-time science communications positions.
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