RETURN MIGRATIONS IN 1877. 163 



It may appear of but little importance to the farmers and agricul- 

 turists of Kansas or Nebraska, on whose fields a swarm of locusts has 

 fallen, to know whether they are from the plains of Montana or from 

 the prairies of an adjoining State ; but if a careful study of their habits 

 shows it to be a general rule that the invading swarms are always, or nearly 

 always, destructive in their operations, and that the local swarms are sel- 

 dom injurious, then this knowledge is important. 



One object of the Commission has been to study carefully this point 

 for the purpose of ascertaining whether there is any difference in this 

 respect between the invading swarms and those which are local or return 

 ing swarms ; not only on account of its direct importance to the agricul- 

 turists of the invaded States, but also on account of its bearing upon 

 the question of their continued vitality in these States. 



Early in the season, when rumors of flying locusts came from the south, 

 the Commissioners in the field were asked to express an opinion as to 

 the result; each, when asked, expressed his opinion without hesitation, 

 and allowed it to be published far and wide : " We do not apprehend 

 any danger from them. In fact this is precisely what th e Commission 

 anticipated, and is one of the strongest possible corroborations of the 

 theory held, that these insects can never become permanent residents 

 of this part of the Mississippi Yalley." 



The result has confirmed to the fullest extent this opinion, and our pre- 

 dictions have been fulfilled in a most remarkable manner. Although 

 from the middle of June to the last of August swarms were constantly 

 moving over Minnesota, Dakota, Iowa, Nebraska, and Kansas, some 

 days covering an area equal to any two of these States, yet in all that 

 time, though visited by myriads after myriads, scarcely a dozen fields 

 in all these States were reported as injured. It may therefore be stated 

 as a general rule, that returning and local swarms do but little injury. 

 It is possible that with a different season the result may be different, 

 but so far as the facts heretofore ascertained are concerned, they point 

 to the same conclusion ; therefore, with the experience of the past season 

 added, we are justified in giving this as one general rule in reference to 

 their habits. 



And right here we beg leave to call attention to the necessity of study- 

 ing carefully what, to many, may at first appear as trivial and unim- 

 portant. Each law ascertained in reference to this species, whether im- 

 portant in itself in an economic or practical sense, is important as an 

 aid or stepping-stone toward the discovery of other laws. 



The discovery of this law in reference to the habits of the different 

 swarms has already been the means of dispelling, in a large degree, the 

 fears the farmers and citizens of these border States entertained in 

 reference to the local swarms. The announcement last season that 

 large swarms had been observed about the middle of May flying north- 

 ward over North Platte, in Lincoln County, Nebr., sent a thrill of alarm 

 throughout that entire State. The fear of such swarms has now de- 



