Insect Swarms under External Perturbations*

In the wild, many animal species form aggregations that behave collectively. Unavoidably, these systems are subject to ubiquitous environmental perturbations such as wind, acoustic and visual stimuli. The way these environmental perturbations influence the animals’ collective behavior, however, is poorly understood, in part because conducting controlled quantitative perturbation experiments in the wild is challenging. To circumvent the need for controlling environmental conditions in the field, we study collective swarms of the midge Chironomus riparius in a laboratory experiment where we have control over external perturbations. In this talk, we consider the effect of laboratory-generated perturbations like air flow or variable light exposure on the swarming behavior.

We find that not only do individuals in the swarm respond to these perturbations by changing their kinematics, but also the swarm as a whole can respond by changing its global properties such as its volume, attraction of individual midges to its center or its pressure, indicative of a collective reaction.