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the extreme northwest of the Republic and in Bolivia. Our 

 information, hoAvever, seems to indicate that there are more 

 outgoing than incoming" mangas. Until these points can be 

 definitely settled, there will remain a doubt as to the existence 

 of a much farther north breeding center and source of supply. 

 It is a point that should be settled, if onh" to remove the doubts 

 that at present exist. 



What height above the surface these swarms ma}' be capable 

 of reaching we cannot say; but that at times they attain an 

 altitude of five hundred or more meters there can be no doubt. 

 Conil mentions a swarm near Cordoba in 18"'3 that reached an 

 altitude of about two thousand meters. This was, perhaps, an 

 exceptional case. Oav observations indicate a much lower 

 altitude, perhaps not more than one hundred to one hundred 

 and fifty meters as the average at which invading swarms fly. 

 At night the insects probabh^ fly somewhat higher than during 

 daytime. According to these figures, then, paraiieusis is a 

 comparatively low flying insect, although in mountain regions 

 they reach altitudes several thousand meters above sea-leve 1 

 as indicated by the fact of their having crossed the Cordilleras 

 into Chile. During recent years this invasion of trans-Andine 

 territor}^ has occurred twice to my knowledge ; viz., in 1891. 

 and again the past year. Several reports have also been sent 

 to headquarters during the past month of large quantities of 

 the dead voladoras being seen among the snowdrifts near the 

 summits of the Andes, where it is surmised that they must 

 have perished from the cold while trying to cross the range. 



The rate at which these insects travel varies greatly accor- 

 ding to circumstances. Perhaps it frequently happens that 

 they do not make more than three or four miles per hour 

 when flying against unfavorable winds, or when there i.s 

 little or none. At other times Avith brisk and favorable winds 

 even fifteen to twent}^ miles an hour may be traversed. Al- 

 lowing from three to six or even eight hours per da}^ for flight 

 at these slow rates considerable distances may be covered in 

 six weeks or two months by a moving swarm. 



The flights oí parai/ei/s/s are chiefly made during daytime 

 in spring, early summer and late fall. In midsummer and 

 early (all when the weather becomes hotter the insects are 

 disposed to remain quiet during the middle or warmer portion 

 of the day. Then towards evening they begin to fly about and 

 shortly before sundown begin their regular migrations. On 



