141 



same conditions may not be duplicated elsewhere, but the ecological 

 relations will in the main correspond to those of India. 



Headlee (T. J.) & Beckwith (C. S.). Some recent Advances in 

 Mosquito Work. —Ann. Entom. Soc. America, Columbus, Ohio, x, 

 no. 2, June 1917, pp. 211-218. 



The ditching and draining operations for mosquito control in New 

 Jersey during the year 1916 are recorded, and some striking 

 changes that have been made in response to the practical needs of 

 mosquito control work are described. It was originally thought that 

 only the marsh where breeding was discovered required diaining, in 

 such a way that Avater would flow in and out with the tide, while the 

 killifish should be afforded ingress at all times to all parts of the salt 

 marsh known to harbour mosquitos. In 1913 it became clear that 

 there were two fallacies in this theory : first, the assumption that 

 the salt marsh has certain breeding areas which may be determined 

 in the course of one or two inspections and which, if drained, will free 

 the marsh from breeding ; and second, the assumption that all salt 

 marshes respond to drainage systems of the above kind. Investigation 

 showed that every undrained area of salt marsh covered with grass or 

 reeds is potentially dangerous, unless frequently covered by the tide, 

 and that even such tide-swept areas may in certain seasons be covered 

 at such infrequent intervals as to permit breeding. New drainage 

 was therefore planned to open all parts of the marsh that were seldom 

 swept by the tide, while areas on which the narrow^ trenching failed 

 to afford protection have been provided with dyke, sluice and tide 

 gates. In 1913 the practice was begun of tracing broods of salt marsh 

 mosquitos by following their flight in motor cars and this method 

 proved very successful. Attempts were made to trace in the same 

 manner the haunts of house mosquitos breeding in a seAvage- charged 

 salt marsh. This necessitated evening collections, which proved so 

 successful that it was considered possible by this process to determine 

 the density of the mosquito fauna throughout the protected area, and 

 thereby check the efficiency of the control work. During 1916, various 

 investigations revealed Ochlerotatns [Aedes) sylvesiris, Theo., as the 

 dominant species in many localities and consideration was given to the 

 problem of its elimination. In Atlantic County, 0. [A.) sollicitans, 

 Wlk., was found to take flight on winds of low velocity, high relative 

 humidity and high temperature. Under other conditions migration 

 is very slow and covers only short distances. The question of the 

 influence of salinity on the development of mosquito larvae and on the 

 distribution of species w^as investigated [see this Review, Ser. B, v, 

 p. 103]. 



Many problems of mosquito work still remain to be solved. 

 Machinery adapted to the work of cleaning and repairing the many 

 ditching systems on the salt marsh should be devised. The fresh 

 water swamp mosquito (0. sylvesiris) has been acquiring predominance 

 over a large part of the protected area, indicating that a further study 

 of its life economy must be undertaken. The oils used as larvicides 

 need to be standardised and a practical larvicide soluble in water or 

 miscible with it should be found. Some practicable method of reducing 

 those mosquitos that have survived the application of the present 



