254 



STATE BOARD OF AGRICULTURE. 



amounts to about half a barrel to an acre. It was usually applied 

 by means of a knapsack spray-pump fitted with a plain nozzle, that is 

 one having a hole 3-32 of an inch in diameter. With this it was possi- 

 ble to throw the oil 20 feet or more in a solid stream and thus to reach 

 far in toward the center of a pond. ' 



Fig. 1.— Map of the Agricultural College and surroundings, cpvering an area of two miles square, or 



four square miles, Original. 



The oil acted perfectly. It immediately spread out into a thin film, 

 covering the water and killing all the pupae within two hours. The 

 larvae required more time, but all were dead in a few hours. The ex- 

 termination was complete, no larvae or pupae being left alive. 



The land about the campus was divided into eight regions, which 

 regions take their names from some land in or near them. The namea 

 are here used arbitrarily and the areas here considered do not corre- 

 spond with the names used in the ordinary sense. Arbitrary area» 



