394 MOSQUITOES OF NORTH AMERICA 



which require more or less attention from three men during most of the open 

 season. They keep the ditches clear, supplementing their work by judicious 

 oiling here and there wherever mosquito larvae are abundant and then have con- 

 siderable time available for perfecting the system and ditching more distant 

 marshes. Experience showed that a considerable number of salt marsh mos- 

 quitos bred on that portion of Jamaica bay northwest of the village were 

 brought in by southwest followed by northeast winds. This led to the extension 

 of ditching operations some 2 miles beyond the village limits. The work in the 

 immediate Aacinity of Lawrence was done partly at public expense assisted by 

 contributions from owners benefited, though it was impossible to secure the co- 

 operation of persons owning the distant marshes, which latter were drained 

 entirely at village expense. The existence of such breeding areas is an imposi- 

 tion upon adjacent communities and it is only a question of time before public 

 opinion will demand a law either compelling owners to abate such nuisances or 

 else provide for their suppression at public expense. The money invested by 

 Lawrence in this work, a total of less than $10,000, has amply justified itself in 

 vastly improved conditions. The village and its vicinity have been entirely freed 

 from breeding places, though occasionally it is subject to late summer invasions 

 by hordes of mosquitos when favorable winds bring them from undrained 

 marshes. Even this will be obviated when the value of the work becomes more 

 generally appreciated and then the cost of the operations will be amply returned 

 in increased land values, to say nothing of the satisfaction accruing from the 

 absence of these dangerous and annoying pests." 



On the north shore of Long Island, in Connecticut, and especially in the 

 vicinity of New Haven, certain simple ditching operations have been carried on 

 which have resulted, at a comparative small expense, in a very considerable 

 reduction of the mosquito supply. 



In California, in connection with work carried on by the California State 

 Agricultural Experiment Station, in 1905, some excellent work was done under 

 the auspices of the Burlingame Improvement Club, in San Francisco, under the 

 direction of H. J. Quayle, of the Experiment Station. The territory involved 

 is included in the upper portion of the San Francisco peninsula, extending from 

 south San Francisco on the north to San Mateo on the south, a distance of about 

 10 miles. The salt-marsh area included consisted of a narrow strip along the 

 San Francisco Bay shore, varying from ^ to 2 miles in width, and 10 miles long. 

 No part of the area was continually covered with water, and it is all above the 

 lowest high tide. The higher tides, however, particularly those accompanying 

 full moon, almost completely submerge the area and result in the development 

 of large broods of salt-marsh mosquitoes. The operations are described as 

 follows : 



" The actual work of control was commenced February 27th, when a gang of 

 men was started to work at ditching on the salt marsh. This work was started 

 near the Blackhawk dairy, where the marshes begin north of Burlingame, it 

 being the intention to work northward toward San Bruno, and make the work 

 permanent as far as we would be able to go in a single season. However, the 

 work went rapidly and the troublesome areas north of Millbrae were not so 

 numerous as was figured, and consequently practically the whole area was 

 covered during the past season. 



" The ditching in the Blackhawk area consisted in connecting the pools and 

 areas of standing water with the tidal creeks in order that they might drain 



