DRAINAGE MEASURES. 51 



perfectly efficient. Citizens' organizations had, for example, done 

 excellent work in the way of destroying household and other fresh- 

 water breeding mosquitoes, in South Orange, Summit, and other 

 inland towns; but occasional inland migrations of swarms of salt- 

 water species necessitated the retention of house screens and dis- 

 couraged the community workers. The salt-marsh species Doctor 

 Smith found to be Aedes cantator, A. soUicitans, and A. t8enior%ynchus. 

 The former is the more northern and earliest, forming the bulk of 

 the specimens on the marshes north of the Raritan River. South of 

 that point cantator makes an early brood only and soUicitans is the 

 abundant species during the rest of the season until late fall, when 

 cantator sometimes reappears. He finds that tdeniorJiynchus is never 

 so common as the others and is a midsummer species. It was a 

 most important discovery when Doctor Smith and his assistants 

 found that all of these species laid their eggs in the marsh mud, and 

 that these eggs may retain their vitality for three years, even if 

 repeatedly covered with water. He found that every time a marsh 

 becomes water-covered some eggs hatch, and if the water remains 

 long enough the larvae reach maturity. On account of the possible 

 long duration of the egg stage the problem seemed to be to permit 

 or even favor the hatching of all of the eggs, and then to provide 

 for the removal of the water so rapidly that none of the larvae could 

 come to maturity. 



To accomplish this end a system has been developed by which the 

 force working under the state entomologist makes deep, narrow 

 ditches in the salt-marshes by means of special machinery. These 

 ditches are 30 inches deep and 10 inches wide, the sides being per- 

 pendicular. The upper 12 or 18 inches of the ordinary salt marsh 

 is peat or turf, and the water drains readily from it. Below this 

 peat is sand, mud, or clay; and at 30 inches a depth has been reached 

 which is below high-w.ater mark and below the point at which vege- 

 tation is likely to start. The ditches are placed from 50 to 200 feet 

 apart, depending upon the character of the marsh, but more often 

 200 feet apart than less. 



Anticipating the ultimate passage of a state bill, work of this char- 

 acter was begun on the Shrewsbury River in 1902, and at the present 

 time both shores are now drained to the full length of the river. 

 In 1903-1904 the marsh areas belonging to the cities of Elizabeth 

 and Newark were drained at the expense of the cities, and in 1906 

 systematic drainage work was begun at the Hackensack marshes and 

 continued along the shores of Middlesex and Monmouth counties, 

 along both shores of the Raritan River, and along the numerous 

 small rivers and creeks running into the Newark and Raritan bays 

 and into the Arthur Kill. 



