Researchers studying swarm behavior of the South American locust Schistocerca cancellata find that the insects’ local population density triggers a phase shift that includes both behavioral and physical changes in the locusts. In a lab, the researchers raised the locust nymphs in isolated or crowded conditions, and the resulting differences in coloration can be seen clearly here. (Image originally published in Pocco et al 2019, Annals of the Entomological Society of America)