214 MOSQUITOES OF NORTH AMERICA 



distance, if necessarj^ to lay their eggs. Where, however, a suitable breeding 

 place lay near at hand they did not appear to pass it over. 



" (2) The maximum distance of flight of A. rossi is not known with certainty, 

 but under the conditions at Mian Mir the experiments showed that they flew to 

 and fro a distance of more than half a mile. 



" (3) The breeding places of A. fuUginosus were in no case nearer than 1000 

 yards from the situation where the adults were captured. 



" (4) In the later part of the season it was difficult to understand where adult 

 A. culicifacies came from unless distances of half a mile or more were traversed 

 by this species. 



" It is obvious that in any attempt to estimate the probable efficacy and 

 practicability of efforts at destruction of ' anopheles,' these conclusions are ex- 

 tremely important." * 



The Sergents in Algeria found that the breeding-places are generally to be 

 found from 100 to 300 meters from infested houses, but in the case of the railway 

 station of Ighzer-Amokran, absolutely isolated in the Valley of the Soumman, 

 the station contained adult Anopheles while the nearest breeding-place was dis- 

 tant one kilometer. The mosquitoes found in the station were in good con- 

 dition. The authors do not mention the possibility that they were brought there 

 in the railway coaches. Further observations by these authors, at Mondovi, 

 showed adult Anopheles at a distance of two Idlometers from breeding-places 

 but they ascertained that this distance was traversed by successive short flights. 



It is obvious, then, that these mosquitoes do not progress by direct flight for 

 considerable distances but usually spread by other means. A succession of short 

 flights, e. g., from areas in which they are abundant, will carry them farther 

 than by any single direct flight. Moreover, the adults are frequently carried by 

 railroad trains and in other conveyances for long distances. This question we 

 have considered in regard to mosquitoes in general in another section. 



That Anopheles perhaps may be carried, exceptionally, for considerable dis- 

 tances by winds is indicated by the observation of Surgeon A. C. H. Eussell, 

 U. S. N. ; he sent us a specimen of A. annulipalpis Arribalzaga, with the state- 

 ment that it was one of a considerable number of mosquitoes blown aboard the 

 U. S. S. Newark in June, 1903, at anchor off Montevideo, more than two miles 

 from the shore. Carter credits Goldberger with the observation that Anopheles 

 alhimanus appeared on board a ship, at Vera Cruz, anchored half a mile from 

 shore. 



In a most suggestive address, delivered before the Section of Preventive 

 Medicine of the Congress of Arts and Sciences at the St. Louis Exposition in 

 1904, entitled " The Logical Basis of the Sanitary Policy of Mosquito-Eeduc- 

 tion," Dr. Ronald Eoss considers the whole question of the spread of mosquitoes 

 from their breeding-places, both in communities in which anti-mosquito work is 

 being carried on and from outside breeding-places from which cleared areas may 

 be restocked. He states that the problem which governs the prophylaxis of 

 malaria through mosquito control may be stated in the following words : " Sup- 

 pose that a mosquito is born at a given point, and that during its life it wanders 



* A Monograph of the Anopheles Mosquitoes of India. S. P. James and W. Glen Liston • 

 Calcutta, 1904. ' 



