54 



settlement. The three problems are : control of the salt-marsh 

 mosquito, of the house mosquito, of the fresh-water swamp 

 mosquito. 



SAI..T- MARSH MOSQUITO. 



The salt marsh problem has been met by thorough ditching, 

 diking and sluice-gating. A total of 916,318 feet of ditching 

 has been installed on the 4,000 acres of marsh in the county; 

 1,000 acres have been put behind dikes and sliuce-gates, and 

 i,400' acres additional have been protected by sluice-gates, with- 

 out a dike. This last method is being tried for the first time on 

 a large area in New Jersey. This system of sluice-gates without 

 the dike is expected to be successful, for the meadow is high and 

 topped only by exceptionally high tides, which occur about once 

 a m.onth, but we think that sufficient reservoir space exists in 

 the ditches to absorb this water without the pools and depres- 

 sions on the meadows becoming filled. A six-foot tide floods, 

 only a zone of 100^ feet around the edge of the meadow. 



The installation of sluice-gates and dike in 191 6 cost approxi- 

 mately $2,000, or a little more than $1 per acre. We consider 

 that about 90 per cent, of the work necessary to control the salt 

 marshes under practically all conditions has been completed. 



HOUSK MOSQUITO. 



Over 1,700 of the larger breeding areas in the county, or 

 55 per cent, of the total number oi swamps and ponds, have 

 been drained. Approximately two-thirds of these have been 

 abated at the expense of the private owners. The total cost of 

 this work is in the neighborhood oi $125,000. We have secured 

 a big reduction in the number of small breeding places located 

 in backyards, etc., as a result of our four seasons' work of yard in- 

 spection. Only 10 per cent, or 15 per cent, of the number of 

 barrels and receptacles existing in yards five years agO' are in 

 existence to-day, and these are kept covered or screened. 



