When did the first winged insects appear?

  Winged insects first appeared in great numbers and variety during the Upper Carboniferous Period. There were many species which are now extinct, notably giant dragonflies. From impressions found in coal deposits, these had wingspans up to 76 centimetres (30 inches). At the same time there were arthropods including spiders, scorpions and millipedes. During the Permian Period, about 200 million years ago, most modern types of insect came into being and by the time of the Tertiary Period nearly all present-day insects existed. Today scientists have identified over 1,000,000 varied species of insects. But this is believed to be only a part of the final total of different types. Some estímales place the actual number as high as four million. Most insects live on land and only a few have adapted themselves to life in water.