After receiving his PhD from the University of Kansas in 1977, Dr. Breed began work as a faculty member at the University of Colorado, Boulder and taught as a Professor in the Department of Ecology and Evolutionary Biology until his retirement in 2019. He taught courses in general biology, animal behavior, insect biology, and tropical biology. His research program focused on the behavior and ecology of social insects, and he worked on ants, bees, and wasps. He studied many aspects of social behavior, including nestmate recognition, division of labor, the genetics of colony defense, the behavior of defensive bees, and communication during colony defense. Dr. Breed was the Executive Editor of the scientific journals Animal Behaviour from 2006-2009 and Insectes Sociaux from 2014-2018.