JANUABY 14, 1916] 



SCIENCE 



75 



The Chicago Section of the society held its win- 

 ter meeting at Columbus, Ohio, in affiliation with 

 the American Association for the Advancement of 

 Science. The next meeting of the society will be 

 held at Columbia University on February 26. 



F. N. Cole, 

 Secretary 



SOCIETIES AND ACADEMIES 



THE BIOLOGICAL SOCIETY OF WASHINGTON 



The 545th meeting of the society was held in 

 the Assembly Hall of the Cosmos Club, Saturday, 

 November 20, 1915, called to order by President 

 Bartsch, with 50 persons present. 



On recommendation of the council Leo D. 

 Miner, E. O. Wooten, A. M. Groves, all of Wash- 

 ington, D. C, were elected to active membership. 



Under the heading Brief Notes, Mr. RadelifiEa 

 called attention to recent efforts of the Bureau of 

 Fisheries in rearing shad in ponds. Young fish 

 thus raised attained twice the size of those of the 

 same age in their natural environment. Specimens 

 of both kinds were exhibited. 



The first paper of the regular program was by 

 Frederick Knab, "The Dispersal of Some Species 

 of Flies. ' ' Mr. Knab said : ' ' The species of Dip- 

 tera that have been spread beyond their natural 

 habitats through the agency of man are for the 

 most part such as thrive under conditions created 

 by man, many of them having even become his 

 inseparable associates. They are mostly scavengers 

 whose larvse thrive in spoiled foodstuffs, sewage 

 and excrement of man or domestic animals. The 

 majority of the flies of such habits occurring in 

 North America are unintentional introductions 

 from Europe. It is certain that many other spe- 

 cies of flies must have been carried across the 

 ocean repeatedly and yet failed to establish them- 

 selves. It is only those species which upon their 

 arrival find conditions suitable for propagation 

 immediately at hand that can be expected to gain 

 a foothold, and most of these will be scavengers. 

 A few striking examples of the wide dissemina- 

 tion of such species by man were given. 



' ' A notable ease is the very wide distribution 

 of Eristalis tenax, the drone fly, within very re- 

 cent times. Its natural habitat was Europe, north- 

 ern Africa and the temperate portions of Asia. 

 It appears to have been first noted in the United 

 States about 1870 and in the course of a decade 

 had spread over the whole country and become 

 abundant everywhere. Osten Saeken already 



pointed out that its sudden spread was only pos- 

 sible ' when the necessary conditions for its exist- 

 ence (drains, cesspools, sewers, etc.) had been 

 gradually introduced by civilization across the im- 

 mense plains which separate the Pacific from the 

 Atlantic Ocean.' Most remarkable is that this 

 fly made its appearance in New Zealand in 1888, 

 where the following year it was abundant in both 

 islands. In America and elsewhere Eristalis tenax 

 has not invaded the tropics. In North America it 

 ranges southward on the Mexican tableland to 

 Mexico City and even to Orizaba at the edge of 

 the tropical belt. But in the temperate southern 

 portion of South America it has become estab- 

 lished with the recent more general settling up of 

 that region. It was first noted at Buenos Aires 

 about 1895 and is now abundant and generally 

 distributed to the Chilean coast. It has become 

 introduced in Cape Colony and the Hawaiian Is- 

 lands, the records for the latter going back to 

 1892. It is also established in southern Australia 

 and appears to have been common about Sydney 

 as early as 1892. 



"A second species, Eristalis arbustorum, has re- 

 cently become introduced into the United States 

 from Europe. Like the other, it is a sewage 

 breeder. It was first noticed about New York 

 City in 1906 and has already spread westward 

 through Ohio. 



"Another recent importation from Europe is 

 the ortalid fly, Chrysomyza demandata. This spe- 

 cies breeds particularly in horse manure. It was 

 first found in Philadelphia in 1897 and is now dis- 

 tributed over the whole United States. 



"Less known are the species which have be- 

 come cosmopolitan within the tropics, but do not 

 invade the colder portions of the temperate zone. 

 Volucella obesa is a large green syrphid fly of 

 scavenger habits. Its original habitat was trop- 

 ical America, but now it is generally distributed 

 through the tropics of the Eastern Hemisphere, 

 occurring even on remote islands, like Hawaii and 

 Goiam. 



"A minute fly of the family Borboridee, Lepto- 

 cera punctipennis Wied. {Borborus venalicius 0. S.) 

 is similarly distributed. Osten Sacken, who knew 

 of its occurrence in Africa and Cuba, suggested 

 that it may have been brought to America by slave 

 ships. This theory appears plausible, as it has 

 since been determined that this fly breeds particu- 

 larly in human feces deposited in the open. Dur- 

 ing the Spanish-American war it appeared in num- 

 bers at Miami, Florida, about the military camp, 

 and where, no doubt, the conditions just indicated 



