Largest Extinct Insect

The largest insect ever know to inhabit prehistoric earth was a dragonfly, Meganeuropsis permiana.   This insect lived during the late Permian era, about 275 million years ago.   These dragonflies had a wingspan close to 30 in. or 2.5 ft  (75 cm) with an estimated weight of over 1 pound (450 g), which is similar to the size and weight of a crow. 

Photo credit: Darren Pepper,