Insects probably appeared 470 million years ago, with the Cambrian appearing at 540 million years ago.-http://www.livescience.com/48663-insect-family-tree-evolution.html-"The timeline established by the researchers indicates that insects likely started colonizing the planet at around the same time as plants, and in some cases, even earlier. Flying insects evolved after complex ecosystems had already developed on land, about 406 million years ago, during the Early Devonian Period, the scientists said.-"Now the researchers know for certain that insects can't be left out of discussions about the ecosystems of, say, the Jurassic Period, about 150 million years ago, Ware said.-"All of the key players were already around before the end of the Jurassic Period. When we picture Tyrannosaurus rex roaming the Earth, we can say there were dragonflies around, and probably grasshoppers and crickets and butterflies," Ware said.-"And the insects that were buzzing and hopping alongside the dinosaurs weren't prehistoric-looking creatures that modern bug lovers wouldn't be able to recognize. The phylogenetic data suggest that these insects were actually very similar to the ones still roaming the planet today, according to Kjer."-Interesting the 'same time as plants'. Looks like good planning as insects feed on plants and help to pollinate them. dhw take note.