On the tensile strength of insect swarms

Phys Biol. 2016 Aug 25;13(4):045002. doi: 10.1088/1478-3975/13/4/045002.


Collective animal groups are often described by the macroscopic patterns they form. Such global patterns, however, convey limited information about the nature of the aggregation as a whole. Here, we take a different approach, drawing on ideas from materials testing to probe the macroscopic mechanical properties of mating swarms of the non-biting midge Chironomus riparius. By manipulating ground-based visual features that tend to position the swarms in space, we apply an effective tensile load to the swarms, and show that we can quasi-statically pull single swarms apart into multiple daughter swarms. Our results suggest that swarms surprisingly have macroscopic mechanical properties similar to solids, including a finite Young's modulus and yield strength, and that they do not flow like viscous fluids.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Biomechanical Phenomena
  • Chironomidae / physiology*
  • Elastic Modulus*
  • Female
  • Male
  • Sexual Behavior, Animal*
  • Social Behavior
  • Tensile Strength*
  • Visual Perception