182 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



7. That such swarms, as a general rule, are not disposed to deposit 

 their eggs iu the visited area, and hence usually perish without oviposit- 

 ing; and also that swarms returning to their native breeding-grounds, 

 although stopping on the way, are not disposed to oviposit until they 

 reach these grounds. 



8. That a sudden change of wind or temperature and increase of moist- 

 ure usually brings down flying swarms. 



9. That timber-belts have a tendency to obstruct their movements 

 and limit their migrations. 



10. That the eastern limit of their range, as heretofore given, appears 

 to be fixed by permanent laws governing the movements of the species, 

 which, so long as the climatic conditions remain as they are, will prevent 

 further progress eastward. 



11. That the insects often fly at night. 



12. That they can, and frequently do, fly so high as to be out of sight. 



13. That their flights may be continued for several days, over a distance 

 of several hundred miles. 



THE CONNECTION OF METEOROLOGICAL PHENOMENA "WITH THE MI- 

 GRATIONS OF THE ROCKY MOUNTAIN LOCUST. 



Anything that can, with our present knowledge, be said on this sub- 

 ject, is necessarily vague and unsatisfactory. That there is an intimate 

 relation between the periodical visitations of the locust and the periodi- 

 cal return of seasons of undue dryness and heat, seems to be probable. 

 That there is an intimate connection between the direction of the 

 wind and the temperature and state of the atmosphere, and the course 

 taken by the locust in its migrations, is also most probable. For exam- 

 ple, it is a matter of general observation, that in Missouri, Indian Ter- 

 ritory, and Texas, namely, the Western Mississippi States, south of the 

 fortieth parallel, the locusts in August and September come with a 

 northerly, but more usually northwesterly wind from the Eocky Moun- 

 tain plateau, and in the spring and early summer, when the winds are 

 from the south and southeast, return several hundred miles in a gene- 

 ral northwest or northerly direction. This general law seems pretty 

 well established, but in places where the winds are very variable, as in 

 Colorado and in Minnesota, it seems impossible to lay down any gen- 

 eral law at present. And in this report we merely propose to state the 

 few facts known bearing on this subject, and leave it for future investi- 

 gation to confirm or disprove the suggestions we have made. 



First, then, as to the recurrence of years of unusual dryness and 

 heat. 



The data=^^ on which to base any conclusions are very meager. The 

 locust region has been so recently settled that, with few exceptions, no 

 records extend back more than thirty years, and in those exceptions 



24 These data liave been collected and arranged for the Commission by Mr. J. S.Kingsley, Salem, Mass. 



