Fleas are not a separate insect order, as previously thought, and are a lineage of scorpionflies, which evolved when they started feeding on the blood of vertebrates sometime between 290 and 165 million years ago (Permian to Jurassic periods), according to a new genetic analysis of fleas and related insects. An ancient flea species called Atopopsyllus cionus may carry evidence of an ancestral strain of the bubonic plague (Yersinia pestis). Image credit:...
