Proceedings of Sixth Annual Meeting 



61 



water which the government records show may reasonably be ex- 

 pected to fall upon this area within any six-day period from the 

 middle of March to the middle of October, with an ample reserve 

 capacity to care for the leakage through the dikes or for unusual 

 storm conditions. 



In view of the amount of work to be done, the limited time and 

 the scarcity of labor, it was obvious at the beginning of the cam- 

 paign that it would be impossible to overhaul the existing drain- 

 age system, complete the new ditching or install the pumping sta- 

 tions in time to control the constantly increasing broods of June, 

 July and August by these means. As the object was to give im- 

 mediate and continuing protection to the many vital war indus- 

 tries in the district, it was necessary to depend to an unusual ex- 

 tent upon the use of oil to control the situation during the devel- 

 opment of the permanent drainage system. 



As neither effective oiling, nor even satisfactory inspections could 

 be made in the presence of the dense vegetation that filled most 

 of the ditches and covered large portions of the marsh areas, the 

 first step was to detail almost the entire available supply of labor 

 to mow the obstructing vegetation and expose the surface of the 

 water. This work was continued without interruption until the end 

 of August. It involved the mowing of millions of square yards of 

 territory and was by far the most expensive item of the temporary 

 control measures. Nevertheless, it was essential to the success 

 of the project. 



At the same time, inspection and oiling forces were organized. 

 As it was impossible to gather more than a nucleus of men ex- 

 perienced in this kind of work, it was found necessary to establish 

 a training school in which intensive instruction in the biological 

 features of mosquito control were given. Inspectors, trained by 

 the Pennsylvania Department of Health, were furnished to the 

 City of Philadelphia and the American International Shipbuild- 

 ing Corporation. Several district inspectors were detailed by the 

 department to supervise the temporary control measures in the 

 various districts, and a general inspector was assigned to check 

 in detail the work of both inspectors and oilers throughout the ter- 

 ritory. A special research inspector and an assistant were em- 

 ployed to make a careful study of the species of mosquitoes to be 

 found in the territory, their seasonal and relative abundance, ques- 



