n6 



SCIENCE-GOSSIP. 



STUDYING THE DIPTERA. 



By E. Brunetti. 



"\ ~K 7HILST the Lepidoptera and Coleoptera are 

 collected by hundreds of enthusiasts, the 

 Diptera, or two-winged flies, seem to be almost 

 entirely ignored by the entomologists of these 

 islands. So far as I am aware there are very few 

 private collections here to compare with the many 

 extensive ones on the Continent, in spite of Britain 

 being as proportionately rich in species as other 

 European countries; though, certainly, she cannot 

 boast of such magnificent forms as occur plentifully 

 abroad. 



As our knowledge of this order of insects is still 

 very incomplete, it offers brilliant opportunities to 

 the earnest student. The life-histories of the vast 

 majority of even the British species are quite 

 unknown, and though Lepidoptera and Coleoptera 

 are being continually forwarded from many 

 countries abroad, there is a remarkable lack of 

 Diptera received from many extensive regions. 



Since Schiner published his "Catalogue of 

 European Diptera," in 1864, containing 677 genera 

 and just over 8,600 species, a sufficient number of 

 new species have been added to swell the total to 

 about 11,500, whilst the number of species existing 

 in the whole world must be absolutely enormous. 

 To give an idea of the unsatisfactory state of our 

 knowledge of this group of insects, I take the 

 liberty of quoting a few figures. Schiner, one of 

 our best authorities, estimated in 1864 the 19,449 

 then known species of Diptera to be distributed as 

 follows: Europe, 8,670; Asia, 2,046; Africa, 1,644; 

 America, 5,517; Australia, 1,056; the remainder 

 being from unknown localities. P'rom 1864 to 

 1868 1,341 new species were described, and in the 

 latter year Schiner, in his " Reise der Novara," 

 computed the probable number of species distri- 

 buted over the whole world to be about 200,000, 

 which to me, at least, does not appear at all 

 an exaggerated estimate. In 1868 Schiner, in 

 the above-mentioned work, accounted for the 

 known species as follows : Cecidomyidae, 348 

 species known (of which 318 were European) ; 

 Mycetophilidae, 694 (571 European, only 3 

 exotic genera) ; Simuliidae, 47 species (27 being 

 European); Bibionidae, 218 (77 European, 108 

 American) ; Chironomidae, 669 (551 European, 93 

 American) ; Psychodidae 30 (19 European) ; Culi- 

 cidae, 132 (30 European) ; Tipulidae, 913 (380 

 European, 358 American) ; Stratiomyidae, 636 

 (136 European, 298 American) ; Xylophagidae, 71 

 (Schiner divided this into three families) ; Taba- 

 nidae, 1,122 (117 European, 516 American) ; Neme- 

 strinidae, 80 (4 European) ; Bombylidae, 1,036 

 (198 European) ; Cyrtidae, 103 (22 European) ; 



Therevidae, 159 (56 European); Asilidae, 1,880 

 (261 European, 687 American) ; Midasidae, 88 

 (3 European) ; Leptidae, 146 (57 European, 68 

 American) ; Empidae, 822 (497 European, 271 

 American) ; Dolichopidae, 822 (399 European, 296 

 American) ; Phoridae, 103 (88 European) ; Muscidae 

 (exclusive of an immense number of species created 

 by Robineau Desvoidy, the large majority of which 

 have since been sunk as synonyms), 7,348, divided 

 as follows : Calypterata — Europe, 2,305 ; Asia, 

 380 ; Africa, 272 ; America, 757 ; Australia, 269 ; 

 unknown, 97 ; total, 4,080 ; Acalypterata — Europe, 

 1,736; Asia, 438; Africa, 211; America 720; 

 Australia, 116; unknown 47; total, 3,268; Syr- 

 phidae, 1,539 (586 European, 520 American) ; 

 Hippoboscidae, etc., 102 (30 European, 26 

 American). It may be noted, by the way, that 

 he does not mention the Conopidae and Oestridae, 

 two families comprising between them from 150 

 to 200 species. In all he computes 20,800 species 

 described up to 1868, of which, say, 9,000 or there- 

 abouts were European. 



Before commenting on these figures, mention 

 must be made of Osten Sachen's valuable and 

 exhaustive " Catalogue of the Diptera of North 

 America," which brings the history of the Diptera 

 of that continent up to the date of its publication, 

 and is a reliable basis for future work. 



We will now glance at the above table of figures, 

 which shows us one or two points of interest. 

 Several great groups of flies up to 1864 had hardly 

 been collected at all out of Europe. These were the 

 Cecidomyidae, of which nine-tenths of the known 

 species were European ; the Mycetophilidae, of 

 which four-fifths were European ; the Chirono- 

 midae, of which five-sixths were European ; the 

 Psychodidae, of which two-thirds were European ; 

 the Phoridae, of which four-fifths were European ; 

 and the enormous group of the acalypterate 

 Muscidae, of which more than half the known 

 species were European. In several families the 

 bulk of the remaining species, after deducting 

 the European ones, were described from America. 



The second thing we learn from the above table 

 of figures is that many families are much better 

 represented abroad than at home ; for example, 

 the Tipulidae, of which, speaking roughly, only 

 one-third of the species were European, one-third 

 being American, and the remainder scattered over 

 other parts of the world ; the Stratiomyidae, of 

 which only one species in six was European ; the 

 Tabanidae, of which no less than nine-tenths of 

 the species were exotic ; the Bombylidae, of which 

 quite four-fifths were exotic ; the Asilidae, of which 



