REPORT ON MOSQUITOES. 123 



relief and against the salt marsh species any other would be idle ; 

 but when local conditions offer a great variety of breeding places 

 that cannot all be dealt with promptly as well as permanently, 

 the best and most prompt effects can be obtained by dealing with 

 the breeding places with larvicides of some sort. Kerosene of 

 low grade and fuel oil seem to produce the best film, and one 

 ounce will cover about fifteen square feet of water area if put on 

 carefully or in a fine spray. As a matter of fact twice that 

 amount or even more is usually applied by means of a watering 

 pot or even a dipper. Applied on the surface of a breeding pool 

 these materials produce a coating that is fatal to both larv?e and 

 pupce when they attempt to pierce it to secure a supply of air. 

 So long as the film remains it will be fatal also to the adult 

 mosquito that attempts to oviposit on it. But the larger the pool 

 and the more exposed it is to air currents, the sooner its effect 

 disappears. In sheltered places the oil may remain visible f.ii" 

 several days and be effective for an even longer time. In un- 

 favorable or exposed places a wind may blow the oil film to one 

 side after a short period, leaving a portion safe for oviposition, 

 though the brood present when the application is made will be 

 killed. The soluble crude oil, Phinotas oil and chloronaptholeum 

 remain effective much longer, rendering the water permanently 

 unfit for mosquito breeding until additional rains dilute them 

 beyond the points at which they kill. In New Brunswick the 

 chloronaptholeum has been used by the local Board of Health 

 with good effect, and it is less objectionable than the others, 

 though more expensive and, on the whole, less active. 



In large hotels, especially at the seashore, there are often 

 indoor breeding places in water tanks, fire buckets, the water 

 cushions under elevators, or in some cases under the buildings 

 themselves. I have known of cases where hotels were infested 

 the year through, the species breeding continuously, and I have 

 record of a factory in which the storage tank for reserve water 

 supply was founcl absolutely swarming with wrigglers. The 

 water in the space below the lower flooring of some of the shore 

 hotels I find is a common occurrence, and accounts for much of 

 the indoor trouble late in the season, when outdoor mosquito life 

 becomes less offensive. In all cases of these sorts practical neces- 

 sities must determine the method to be used. Enough has been 

 said to serve as a guide to any intelligent man before whom such 

 a condition may present itself indoors. 



It should be kept in mind always that any body of water, no 

 matter how small or however foul, is likely to serve as a breed- 

 ing place; but it should also be kept in mind that there are many 

 bodies of water where the insects do not breed, and it behooves 



