What are Diptera?
Diptera is the order of two-winged insects commonly named flies. Though they may officially be named as flies, the order also includes midges, gnats, mosquitoes, etc.
More information about Diptera in general can be found here:
CSIRO Diptera homepage (Australia)
USDA Diptera homepage (U.S.A.)
Museum of Paleontology, University of California, Berkeley
Gordon's Fly Page (Diptera)