Airplane Dusting in Control of Malaria Mosquitoes H 



used was considerably more than enough to cover the field. For the 

 whole cut an estimated mortality of 73 per cent resulted, but with 

 the exception of the one edge practically 100 per cent of the large 

 larvae were destroyed as well as the majority of the small ones. In 

 this connection it may be noted that when mortality of the larvae is 

 not complete those from one-half to full grown are always the first 

 to succumb. 



The level nature of the rice fields made very favorable conditions 

 for airplane dusting, and the only difficulties in the way of effective 

 treatment appeared to be in the case of fields adjoining the woods or 

 where the hedgerows along the ditch banks were high. Some of the 



Fig. 



-Growth of water chinquapin in Blue Front Lake at the time of the dusting 

 test in 1924 



dust was wasted because it remained on the leaves, but when these 

 were dry the mixture did not adhere to them to any great extent. 

 It was found from other experiments that the leaves of the rice plants 

 are very susceptible to burning when a large quantity of Paris green 

 is used, but the quantity necessary to kill Anopheles larvae did not 

 prove destructive to the plants, and in a few small plat tests, where 

 excessive quantities were applied, even severe burning of the leaves 

 did not appear to kill the plants or to prevent normal development 

 of the grain. 



The summaries of the dusting operations in 1924 are given in 

 Tables 3 and 4, which include the records for the individual stations. 



