We should all learn from the coleopterists in Bugguide. They decided to collect at least one specimen from each of the families in that group and they are almost there. Wouldn't it be ironic that the order with the largest number of families complete that list before anybody else?
Here are the families still missing from Diptera, Hymenoptera and Lepidoptera. I used Nomina Nearctica for the first two and All Leps for the last one. I am sure that there are some mistakes, so please, let me know. The thing is, let us go out there and try to get those families in Bugguide!
If somebody wants to work on a similar list for Hemiptera, feel free to do it; otherwise, I may try to do it myself at a later time.
Diptera See Keith Bayless update at 179556
Acartophthalmidae
Asteiidae
Axymyiidae
Braulidae, Bee lice
Camillidae
Canaceidae, Beach flies
Corethrellidae, Phantom midges
Cryptochetidae
Curtonotidae
Cypselosomatidae
Deuterophlebiidae, Mountain midges
Dixidae, Meniscus midges
Hilarimorphidae
Nycteribiidae, Bat flies
Nymphomyiidae
Pachyneuridae, Dark-winged fungus gnats; Root gnats
Pelecorhynchidae
Periscelididae
Ropalomeridae
Streblidae, Bat flies
Strongylophthalmyiidae
Tanypezidae
Tethinidae
Thaumaleidae, Solitary midges or trickle midges
Vermileonidae, Worm lions
Hymenoptera (11 families)
Agaonidae, Fig wasps
Anaxyelidae, (only one species: cedar wood wasp,
Syntexis libocedrii)
Elasmidae
Embolemidae
Oxaeidae
Perigidae
Rhopalosomatidae
Sclerogibbidae
Signiphoridae
Tanaostigmatidae
Tetracampidae
Lepidoptera (16 families)
Acanthopteroctetidae, Archaic sun moths
Acrolepidae
Chimabachidae
Copromorphidae, Tropical fruitworm moths
Dalceridae
Deoclonidae
Doidae
Douglasiidae, Douglas moths
Epermeniidae, Fringe-tufted moths
Epipyropidae, Planthopper parasite moths
Heliozelidae
Hyblaeidae, Teak moths
Lyonetiidae
Peleopodidae
Sematuridae
Tischeriidae, Trumpet leaf miner moths