CHAPTER VI 

 INLAND DRAINAGE 



IMPORTANCE OF DRAINAGE AS AN ANTI-MOSQUITO MEASURE 



Drainage is one of the most reliable and permanent methods of 

 mosquito control. Where there is no water in which the mos- 

 quito eggs may develop, there can be no mosquitoes, and when 

 once a place is properly drained, it should remain in good shape 

 for a considerable period, with a certain amount of maintenance. 

 Unless the anti-mosquito work is a mere temporary expedient, 

 therefore, drainage will play a large part in it. 



The term "drainage," however, as applied to anti-mosquito 

 work, signifies a procedure somewhat different, as a rule, from 

 drainage for agricultural and other purposes. Such drainage 

 work, as a matter of fact, sometimes produces mosquito breeding- 

 places. For mosquito eradication, the land must not only be 

 properly drained, but the ditches themselves must be so designed 

 as not to become sources of breeding. 



Drainage, as an anti-mosquito measure, may include any or all 

 of the following, and maintenance thereof: Ditching, open and 

 lined; sub-surface tile drains; vertical drainage; re-channeling 

 of natural water-courses; filling; diking; construction of tide-gates; 

 pumping. 



The last three will be considered in the chapter on "Salt Marsh 

 Drainage," since it is in salt marsh work that they are generally 

 employed. 



In addition to being a most effective measure by itself, drainage 

 frequently may be used to great advantage in connection with 

 fish-control, oiling and other procedures. Examples of such 

 cases are : Construction of a ditch connecting an isolated, Ashless 

 pool with water stocked with mosquito-destroying fishes, or low- 

 ering of a pond to reduce the area that requires to be oiled. 



LIMITATIONS OF DRAINAGE 



While drainage, in the long run, probably is considerably 

 cheaper than most other control methods, especially oiling, it 



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