122 Mosquitoes 



Lily ponds or watering troughs, where oil is undesir- 

 able, should be stocked with small fish, and as the 

 larvae congregate and eggs accumulate around the 

 margins of such places, the edges of the water must 

 be deep enough to permit the fish to work. Long 

 grass and weeds, unnecessary vines and bushes where 

 the adults may hide, should be cleaned up, lawns cut, 

 vacant lots kept clear of growth, and tree holes filled. 

 Sewer catch-basins should be oiled two or three days 

 after each heavy rain, and about eveiy ten days 

 thereafter. If it rains heavily about the end of the 

 ten days they are safe for a few days more. But it 

 should be remembered that a very little rain will wash 

 the oil down the sewer, and it takes a fairly heavy 

 downpour, as a rule, to wash out the eggs and larvae. 



Chemical Destroyers. — If one does not object to 

 the odour, kerosene or fuel oil are cheap and sufficient 

 remedies, especially for sewer catch-basins. Soluble 

 crude petroleum, Phinotas oil, or chloronaptholeum 

 may be used. The last is quite expensive, but, as it 

 poisons the water thoroughly and becomes mixed 

 through it, it continues effective against the larvae for 

 some time, even when considerably diluted. It does 

 not, however, kill the pupae, nor does it act well in 

 water containing more than a trace of salt. This 

 preparation, sold by the West Disinfecting Co., of 

 New York, costs $ [ .00 per gallon, and should be used 

 at the rate of 1 part to 50 parts of water. It is a 

 disinfectant as well as a larvicide, and is good to use 

 in places where oil would be found objectionable. 



Phinotas oil is the most effective of all larvicides, 

 both suffocating by film and poisoning the larvae. It 



