27i THE MOSQUITOES OF NEW JERSEY 



twenty inches in depth will bring about sufficient circulation of tidal 

 water and provide adequate drainage to prevent mosquito breeding. 

 Accordingly most recently constructed ditches on the open salt marshes 

 have been limited to depths of from twenty to twenty-four inches. This 

 phenomenon of washing out of underlying soil and softening of ditch 

 banks is also contributed to by the presence of a strong tidal suck. The 

 effect of this tidal suck can be cut down by placing ditch boards at the 

 opening of the ditches, the top of which is the height of the bottom of 

 the ditch and by outletting insofar as possible these ditches into creeks 

 and thoroughfares where the tide range is not so great. 



Insofar as the nature of the marshes will permit, these ten-inch circle 

 ditches are opened into the natural creeks that meander through them. 

 When such drainage is impossible, large main ditches, as wide as may 

 be necessary, are cut as outlets. 



In cutting the ditches it is best to remove the sod in pieces ten inches 

 wide, by six to eight or more inches thick, the length being equal to the 

 depth of the ditch because these large pieces are heavy, not easily moved 

 by the tide, and can be conveniently carted away by the landowners. 



Much experience with the floating of sods taken from these ditches 

 has been accumulated in the course of the last two decades. Whether the 

 sod consists of pieces as described above or of long ribbons, sooner or 

 later through loss of water they become light enough to float. When the 

 marshes become covered deeply by tide these sods are lifted and carried 

 hither and yon. Most of them seem to be carried toward the inner edge 

 of the marshes and deposited, and others are carried out in the channels 

 and bays. Eventually they become sufficiently water-soaked to sink to 

 the bottom. In this way creeks and thorofares, especially the latter run- 

 ning through the marshes, become so choked in places that their navi- 

 gation by motor boats has been greatly reduced. In some cases these 

 sods have been carried to oyster beds, forming mud sills and causing the 

 destruction of some oysters. It is obvious that no sods should be left 

 on top of the marsh. Special machinery has been developed for the pur- 

 pose of cutting these ditches, chewing up the sods and eliminating the 

 sod problem. 



In every area ditched thus far, small shallow pools have been found 

 which do not drain readily into the neighboring ditches and which are 

 too small to merit drainage by means of a spur. Such holes are filled 

 with sods from the ditches. After the sod filling has been thrown in, the 

 surface of the rough pile is broken up and smoothed off. In a few years 

 the grass grows over the fill, obliterating the hole. 



The past two decades have witnessed some very important changes in 



