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ol' the country since the direction t;iken b}' moving mangas is 

 more or less regulated by prevailing Avinds, surface conii- 

 guration, temperature, humidit3', and food-suppl}'. In some parts 

 otthe country these general movements, and the courses taken 

 bAi" the insects concerned in them, are ver3^ well defined. In 

 others our information is still so meager that nothing definite 

 can be stated Avith regards to such movements even if the}' 

 occur. 



iVpparently the locusts which start from the "central" winter- 

 ing grounds early in August move southward and begin 

 developing eggs a little later. Some of them maturing earlier 

 than others, the females thus encumbered must necessaril}- 

 drop down and remain behind to deposit their quota. Others 

 with the eggs less advanced move on and in turn also ripen 

 and deposit them; while still others go mtich further into the 

 settled districts before egg-laying is forced upon them. Vn this 

 manner, Avith favoring wind and weather, in a month or two, 

 locusts that have wintered along the Rio Salado in northern 

 Santa-Fé, may reach even the Rio Colorado, or beyond, as Avas 

 shown the past spring. By the process of dropping out as their 

 ■eggs had developed the entire route became stocked with eggs 

 <and later with the saltonas. 



When these latter have acquired wings a northward move- 

 ment begins; but instead of passing back over exactl}- the same 

 route followed by the outcoming insects, the return llight is 

 made first to the west, northwest, then north, and finallv 

 northeast— these directions being apparently regulated b\' 

 prevailing Avinds, surface configuration, temperature, etc., as 

 mentioned above. In other words, there is a sort of circular 

 movement to be noticed if we combine the directions taken by 

 the invading and returning mangas. 



Whether or not the progeny of these insects which move 

 away from this central Avintering region to the northeast and 

 north, foUoAving up the Parana and Paraguay rivers, succeed 

 in returning to this locality cannot be definitel}' determined 

 from the very meager data at hand. But that these directions 

 are less frequently taken by insects leaving the Avinter 

 quarters is quite evident from the numerous statements of 

 correspondents to the elVect that the regions under considera- 

 tion are less often visited by invading SAvarms. 



It is impossible also for similar reasons to make any definite 

 statement concerning these invading and returning mangas in 



