Insect order diptera, the true flies (diptera means two wings), are believed to have first appeared during the Triassic more than 200 million years ago. Thus, they appeared during the great radiation of insects following the Permian extinction. The term Diptera is actually a misnomer; most members have a second, vestigial pair of wings that are mere knobs that are used as a "gyroscope" to keep the insect level in flight. So exquisite is insect design that most groups were well formed by the Cretaceous and remain largely unchanged in appearance during modern times where some 150,000 species occur worldwide, inhabiting every imaginable environment.

Gallery of Diptera Fossils
Biting Midge Swarm Order Diptera Family Ceratopogonidae Upper Eocene to Lower Oligocene Kaliningrad District, Russia	Long-Legged Fly Family Dolichopodidae Upper Eocene to Lower Oligocene Kaliningrad District, Russia	Dark Winged Fungus Gnat Family Sciaridae Upper Eocene to Lower Oligocene Kaliningrad District, Russia	Asilidae: Robber Fly and Tipulidae: Cranefly Green River Formation, Utah
Robber Fly Order Diptera Family Asilidae Lower Cretaceous Crato Formation, Brazil	Mosquito in amber, an exceddingly rare amber inclusion	Robber Fly Family Asilidae Lower Cretaceous Yixian Formation, Liaoning Province of China	Non-Biting Midge, Family Chironomidae in Baltic Amber
Dipteran in amber	Sand Fly in fossil amber Family: Psychodidae Subfamily: Phlebotominae	Family Sciaridae (Fungus Gnat) Dominican Republic Amber (oligocene to Miocene) This fungus gnat may have been in nuptial flight. The "pincers" at the end of the abdomen is that of a male and was the means by which he would have grasp a female.
Dipteran in amber	Spider and fly in amber	Oligocene Robber Fly in shale from Idaho. These members of Family Asilidae are aerial predators capable of attacking bees, wasps and other insects larger than itself.	Crane fly in amber.
Dipteran in amber	Hump-Backed Fly or Scuttle Fly Family: Phoridea Note well-faceted eyes affording a detailed view of the fly's surroundings. The other common name for this family is Scuttle Fly, descriptive of their habit of scurrying around in agitated fashion.	This is a large (11 mm body) member of the Order Diptera, Family Asilidae, or Robber Flies, in Colombian amber. These flies today occur in a number of habitats, and are highly predaceous, attacking insects much larger than themselves.	You would probably avoid this insect with its wasp-like appearance, complete with "stinger". It even has banding of the abdomen such as you would expect from a wasp. Closer inspection, however, reveals two knoblike projections on its back. These are known as halteres, and are a trademark of the order Diptera.
	Various dipterans in amber.	Family Psychodidae (Moth Fly) Oligocene to Miocene Dominican Republic Moth flies are found today in numbers around drains, and their larvae are found where decaying matter is prevalent. They are the relatives of the Sand Flies, a group of biting flies responsible carrying many diseases in the tropics. Moth flies, however, do not bite.