1917] Some Recent Advances in Mosquito Work 213 



fact, this continued to be the thought until 1913, when it 

 became clear to the senior author and others that there were at 

 least two fundamental weaknesses in the working out of this 

 plan. The first was 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. The second was the assumption that all salt 

 marshes respond to drainage systems of the above sort. 



In 1913 the senior author was led to suspect and in 1914 to 

 prove that certain areas in the salt marshes of the upper Hacken- 

 sack Valley, which had been reported as in non-breeding ter- 

 ritory, were really at times very prolific producers of salt marsh 

 mosquitoes. This experience has since been repeated "so fre- 

 quently at different points of the supposedly drained salt marsh 

 that the writers are convinced that every undrained area of 

 grass, cattail or reed covered salt marsh is potentially dangerous 

 unless it is swept with great frequency by the tide; and that 

 even such tide swept areas may, in certain seasons be covered 

 at such infrequent intervals as to permit breeding. 



In 1914 the drainage systems established in Essex and 

 Union Counties on the original plan utterly failed to prevent 

 the issue of an enormous brood of salt marsh mosquitoes between 

 July 15th and 20th. The failure was directly traceable to an 

 unusual combination of long continued, extremely high tide 

 with a period of much rain and cloudy weather. Other 

 parts of the coast served with the same system of ditching, 

 in many instances in a less completed state, were adequately 

 protected. The difference seemed to lie in the fact that the 

 east w4nd banked the waters up in land-locked Newark Bay and 

 created a condition which did not obtain along the more open 

 parts of the coast. 



Although this failure was chargeable to an unusual condition 

 of tide and weather, it was made possible^ by peculiar geograph- 

 ical location and might any year be repeated. It was, therefore, 

 sufficient to condemn the system and to indicate that some 

 radical change must be made. 



After carefully considering the matter it was decided that 

 the most feasible plan was to keep the sea off the marshes by 

 dikes, to outlet the water through sluices and tide gates, and 

 thus create a reservoir capable of absorbing heavy rainfall 



