LARVICIDES 299 



across the entire windward side at a more leisurely pace. After the 

 flight ceases, mosquito annoyance in the area will be negligible for the 

 balance of the evening. 



"Care should be taken to be ready to move the spraying equipment at 

 a moment's notice in the event the wind should shift while the dusk flight 

 is in process. 



EQUIPMENT 



"For areas of less than 2,500 square feet a three or five gallon com- 

 pressed air hand sprayer, such as the 'Hudson, Jr.,' will produce satis- 

 factory results when equipped with a mist nozzle. For larger areas a 

 high pressure spray pump capable of developing 300 to 600 pounds 

 pressure, mounted on a light, fast truck, is advisable. Sufficient hose 

 and mist guns should be available. If the pump can be operated from 

 the power take-off of the truck much of the engine noise is avoided. The 

 larvicide should be agitated continuously and not left in dilution for 

 any length of time. 



"Strict care should be exercised to avoid contact with the guests. 

 Although it is often humorous to permit the mist to drift over the 

 guests, it is entirely unnecessary and creates a bad impression. 



"Limit the help to those absolutely necessary for the quick, efficient 

 handling of the hose and guns. Three men, including the director and 

 truck operator, are sufficient to control an area up to four acres under 

 all normal conditions." 



MACHINERY FOR DISTRIBUTING LARVICIDES 



The objective sought in the distribution of larvicide, whether oil or 

 the New Jersey Larvicide, is the establishment of a killing film over 

 waters in which mosquito wrigglers are developing. When the larvicide 

 is delivered as a finely divided spray, it effects this cover most quickly 

 and satisfactorily. 



DeKvery through a small-holed nozzle under high pressure or atom- 

 ization seems to accomplish this fine division. The fineness of division 

 in the first instance is the result of finding the proper relation between 

 size of nozzle hole and pressure under which the liquid is forced out. 

 Small holes are required when low pressure is used and the area-cover- 

 ing capacity of the machine is correspondingly limited. With high pres- 

 sures (300 to 600 pounds per square inch) the nozzle hole can be much 

 larger, and the area-covering capacity is consequently increased. The 

 fineness of division in the second instance (atomization) is dependent 

 upon the relation of the speed of liquid delivery to pressure of the air 



