396 MOSQUITOES OF NORTH AMERICA 



" After these repairs were completed the gates were operated, opened at low 

 tide and closed at high tide, for a week, but at the end of this time there was 

 still much water in the area, because the gate floors were not low enough to lower 

 the water level sufficiently. This made it necessary to lower the gate floors and 

 add an extension to the gates to reach the lower level. This being done the gates 

 were again operated for several days, but it was found that, due to seepage of 

 water through the dike in many places, hand operating would have to be kept up 

 almost indefinitely. It was, therefore, necessary to replace these old-style gates, 

 operated by hand, by automatic ones, and these were, consequently, put in at 

 both the upper and lower gates, and the floors lowered 32 and 20 inches respect- 

 ively. These gates were made to swdng on an axle at the top, the lower end being 

 free and easily moved by the pressure of the water, so that at low tide it was 

 opened by the pressure of water on the inside, and closed as the water from the 

 high tide rose on the outside. 



" This tidal creek which served as an outlet for the lower gate had become 

 filled in to a depth of 2 or 3 feet during the period the gate was closed, and this 

 was cleaned out for 300 or 400 yards toward the bay in order to drain out the 

 area inclosed by the dike. 



" With this work done upon the dike the area inclosed by it was treated in 

 much the same way as that outside, except that the network of cracks, already 

 mentioned, had to be filled in in many places, and several of the tidal creeks 

 deepened. The reward for all this work came later in the season when the area 

 was changed from a veritable breeding ground to the safest portion of the marsh. 

 Indeed, this area was the key to the situation, and the excessive abundance of 

 mosquitoes in this particular territory was without doubt due to this extensive 

 breeding ground. 



" It is appropriate to mention here the connection of this work with the 

 reclamation of marsh lands. This tract of 500 or 600 acres, which had been 

 useful only for duck-hunting, is now thoroughly dry and could be put to agri- 

 cultural uses at very little additional expense. Such work has already been ex- 

 tensively taken up on the marshes below San Mateo, and it has been found that 

 a good crop of grain can be raised on such land in the second year of its cultiva- 

 tion. It is safe to predict that all the marsh land involved in the present cam- 

 paign will be under cultivation before many years, and because of its proximity 

 to the metropolis of the coast should be very valuable. 



" Besides the marshes already mentioned, permanent control work was done 

 on the marsh about Millbrae and northward to San Bruno, and also some drain- 

 age work at Coyote Point, opposite San Mateo. The work at these places was 

 much the same as that already described, and further details are unnecessary. 



" In addition to this permanent work there was some oiling done on the marsh 

 where the ditching and filling work were not rapid enough to keep ahead of a 

 developing brood. The total amount of oil applied, however, did not exceed 400 

 gallons, and most of this was applied to the large tidal creeks in the reclaimed 

 land opposite San Mateo. The remainder was applied to pools where wrigglers 

 appeared after a high tide, and, the brood being checked, we had until the next 

 high tide in which to make the pools permanently safe." 



During 1908, 200 acres of salt-meadow land on the shore of Little Neck Bay, 

 between Bay City and Douglaston, Long Island, were drained by simple ditching 

 measures. This work was done at the instigation of the Bay Side Park Associa- 

 tion and the Douglaston Civic Association, both associations forming a Joint 

 committee to promote the extermination of mosquitoes. They went to the 



