Aerial Cannibals

October 22, 2015

Nature Notes by Bill Dunson

If you are at the beach you might look up and notice that an interesting migration of dragonflies is taking place just over your head. Dragonflies are heading south to escape the frozen north in considerable numbers and I watched many common green darners passing by at Caspersen beach, Venice, FL, on Oct. 21. It may surprise you that relatively primitive insects such as dragonflies are capable of such long distance migration. They are extraordinary flyers but they apparently get hungry while flying and their appetites take a bizarre turn. This species is common around our farm ponds in VA so it is interesting to see where they go when they leave and are replaced by the equally large, but cool weather tolerant shadow darner.

I saw several twosomes of common green darner dragonflies writhing on the road and on closer inspection realized that one of the pair was eating the other! The dragonfly on top had its jaws embedded into the thorax of the victim. I knew that falcons often eat migrating dragonflies but did not realize that these predaceous insects could and would eat their own species.

Bill Dunson

About Bill Dunson

Bill Dunson, born in rural Georgia, skipped 12th grade and went directly to Yale. Bill subsequent-ly received a PhD in Zoology from the University of Michigan, studying softshell turtles. Bill is Professor Emeritus of Pennsylvania State University thanks to a career spent entirely at that institution, teaching and doing research on the physio-logical ecology and ecotoxiciology of reptiles, amphibians and fish. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. He has served on many advisory boards here in Southwest Florida to preserve the water that gives life to our region.

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