ENTOMOLOGY . 265 



In order to study locusts in the laboratory, consignments of the 

 living insects and their eggs have been brought to this country by 

 air on several occasions. They breed readily in captivity so that 

 detailed experiments on their bionomics are possible. Such have 

 already been made at Pretoria University, by the Imperial Insti- 

 tute of Entomology in the British Museum (Natural History), 

 the Imperial College of Science and Technology, London, and 

 Cambridge and Birmingham Universities. In particular, Professor 

 J. C. Faure, working at Pretoria in 1932, succeeded in changing 

 each species from the solitary into the migratory phase under 

 experimental conditions. If only work such as this could be carried 

 on in laboratories simultaneously with field work at full strength, 

 from now until the next wholesale outbreaks occur, knowledge 

 might be expected to have advanced far enough to have real effect 

 in control when occasion demands. 



A recent development, which promises a certain degree of 

 success in the defence of crops, is spraying flying swarms with 

 poison dust from aircraft. Experiments with different poisonous 

 substances for the purpose have been made on living locusts in 

 the Sudan and in England, under the Economic Advisory Council, 

 and the process was tested to some extent during 1934 in Rhodesia 

 on flying swarms with the aid of Imperial Airways craft fitted for 

 the purpose. The Union is experimenting by spraying settled 

 swarms with a more simple apparatus. There are many technical 

 difficulties with regard to air spraying; arsenical powders, for 

 example, are dangerous to stock and to man, and cannot at present 

 be guaranteed not tp cake. The present situation with regard to 

 this aspect of locust destruction is that some degree of success has 

 been attained with arsenic, but a technique for its safe use in 

 populated country has not yet been evolved. If a substitute which 

 is non-poisonous to man and beast can be found, dusting from 

 aeroplanes will have great possibilities. In the meantime, baits 

 made of bran, or other similar material, moistened with arsenical 

 solution remain the best method for extermination of locust 

 swarms. 



Up to now measures of direct control have seldom proved 

 efficacious, except in highly cultivated areas, and it is somewhat 

 anomalous that the sums of money expended in the wholesale 



