Large groups of swarming midges are composed entirely of males, where their combined motion generates high-pitched sounds that attract females. Physicists are among the scientists trying to understand the underlying principles of “collective behaviour”, which is observed in a range of biological systems. Insights from their work could lead to real-world applications such as crowd-management strategies and smart energy networks that are more resistant to catastrophic failure. Find out more about the research in this feature by Jennifer Ouellette originally published in the February 2018 issue of Physics World.