62 , N. J. Mosquito Extermination Association 



tions of duration, extent and direction of flight, of invasions from 

 adjacent areas, and such other biological conditions as might af- 

 fect the work. 



Because of the great extent of the open breeding areas, the cer- 

 tainty of invasions from outside areas, and the new sparsely set- 

 tled sections, no house-to-house inspections were undertaken. It 

 was planned to make a complete field inspection of the entire ter- 

 ritory on an eight day schedule, with oiling gangs of five to eight 

 men directed by foremen to follow the inspectors and destroy the 

 breeding reported. 



Central oil stations with steel storage tanks of 500 to 1,000 gal- 

 lons capacity were located at convenient points in the territory. 

 Men and supplies were transported by horses and wagons, and 

 motor trucks as close to the work as practicable. The large ex- 

 tent of the marsh areas and the lack of roads in many sections 

 made it necessary to carry oil and equipment by hand for long 

 distances over difficult ground. The magnitude of this phase of the 

 work is indicated by the fact that, in spite of the exceptionally 

 dry summer, an average force of forty oilers was maintained 

 until the first of October and a total of 55,000 gallons of oil was 

 used. 



The research work carried on by the department disclosed the 

 fact that the predominant species of this district, after the dis- 

 appearance of the June brood of Aedes sylvestris, was Culex pipiens, 

 which bred almost universally, due, undoubtedly, to the fact that 

 the sewage-charged waters of the Schuylkill River and the smaller 

 streams find their way into the enclosed areas by way of the rat- 

 holes in the dikes and the leaking tide-gates. 



Anopheles qiiadrima^culatus and Anopheles punctipennis, were 

 likewise taken in every section, but in relatively small numbers. 



Abundant breeding of Aedes sollicitans, the typical salt marsh 

 mosquito, was observed in South Philadelphia, fifteen miles above 

 the uppermost reaches of salt water. The larvae of this species 

 were confined to those areas within range of the industrial wastes 

 discharged upon the marshes at the rate of approximately 5,000,000 

 gallons per day by the Pennsylvania Salt Manufacturing Company. 

 This concern is engaged primarily in the manufacture of alum. 

 The wastes contain a trace of acid and a considerable proportion 



