PACKARD J 



THE illGEATIOXS OF THE LOCUST. 



641 



The locust is quite or nearly as destructive in Africa, Asia, and 

 Soutberu Europe as in this country, but the laws of their migrations 

 and their conuection with meteorological phenomena have never been 

 studied in those regions, and it remains for the United States, with its 

 Weather Signal Bureau, to institute, in connection with tlie scientific 

 surveys of the West, investigations regarding the nature of the evil and 

 the best means to overcome it. 



In endeavoring to trace the connection between the migrations of the 

 locust and the course of the winds at different months, the writer has 

 been led into some theoretical considerations which seem to be supported 

 by the facts presented in the unpublished report, and which may be 

 confirmed or disproved by future investigations. 



History of the migrations of rhe locust. — The following table, compiled 

 from the reports of A. S. Taylor, the late Mr. B. U. Walsh, Prof. C. V. 

 Riley, Prof C. Thomas, Mr. G. M. Dawson, and the observations of Mr. 

 W. N. Byers, together with the reports in the Monthly Weather Eeview, 

 will show the years when the locust was excessively abundant and de- 

 structive in the different Territories and States, and also serve to 

 roughly indicate the frequency and extent of the migrations of the de- 

 structive locust of the West. The dates which are starred are years 

 when the progeny of the locusts of the preceding year abounded, and 

 when in most cases there were no tresh incursions from the westward. 

 The species referred to under the head of California, Washington, and 

 Oregon may be some other than Caloptenus spretus. 



This table and the data on which it is based are necessarily very im- 

 perfect, owing to the vast extent of the territory over which the locust 

 swarmed, and the fact that the greater portion isuninh'ibited, while the 

 inhabited portions have been settled only within comparatively few 

 years. It will be seen, however, that since 1873 the evil has been greater 

 and maie widespread than ever before. 

 _ The theory of the migrations. — (1) The immediate cause of the migra- 

 tions of the locust from its original breeding places is the unusual abundance 

 of the species during certain years. It has been found in some cases that 

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