SELECTED PAPERS 



mended that an international service be established, a project that has 

 not yet been activated in consequence of the outbreak of the war. But 

 since 1930 the 'Anti-Locust Research Centre' has been working in 

 London, coordinating the data supplied by numerous countries, and 

 sending out warnings and predictions based on these data. 



During the war years the British Government initiated important 

 international research on a smaller scale concerning the fight against 

 the so-called desert locust, whose swarms threatened the food sources 

 of East Africa, the Middle East, and British India. This species breeds 

 in the British Sudan and Eritrea, migrates from here via the Dead Sea 

 to Arabia and Northwest India, whence it invades the entire territory 

 surrounding the Persian Gulf. From Arabia it generally threatens the 

 valley of the Euphrates, Syria, Palestine, and the Nile Delta. Closely 

 cooperating teams of English, Egyptian, and Indian investigators 

 have kept Arabia under control, while Russian missions have provided 

 additional support in Iran. I cannot enter into details concerning the 

 manner in which the war against the insect has so far been prosecuted, 

 and merely indicate that trenches, wire obstructions, flame throwers, 

 and airplanes took their place among the means of combat. Even more 

 important is, however, the fact that particularly during the past few 

 years poisoned bait has become dominant owing to the manufacture 

 of certain chemicals, extremely small amounts of which can kill in- 

 sects whereas they are but little poisonous to higher organisms. This 

 method consists in mixing some foodstuff that attracts locusts, such as 

 moist bran, with 0.5 per cent of crude hexachlorobenzene, containing 

 around 13 per cent of the toxic 'gammexane'. An experienced erad- 

 icator may kill five million locusts per acre with only 2.5 kg of poi- 

 soned bran, containing only 2 g of the insecticide proper. 



Although this topic could be expanded practically indefinitely, I 

 shall refrain from further elaborations, not, however, without just rai- 

 sing the spectre of the calamity that Europe would suffer if a relaxa- 

 tion of human vigilance were to lead to a destruction of our potato 

 crop by the dreaded Colorado beetle which has already been collected 

 in our country in litre quantities. 



I may not neglect to remind you of the fact that it is not only in- 

 sects that threaten our food crops. It is generally known that in 1845 

 and 1846 Western Europe suffered from famine because the fungus, 

 Phytophthora infestans, annihilated a large proportion of the potato har- 



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