96 



The Rocky Mountain Locust. 



slow. They occupied nearly a month reaching from North- 

 western Iowa to the southwestern limit in the same State, 

 and their eastward progress on the confines of the limit- 

 line already indicated was still more gradual as they went 

 south. All of which indicates that they fly most power- 

 fully when leaving the higher altitudes of the Northwest, 

 and most persistently during the first week or so after be- 

 coming fledged, while the females are not yet prompted to 

 descend for oviposition. This is also the period when they 

 are passing over the vast plains and the sparsely settled 

 and uncultivated portion of the country, in which there is, 

 perhaps, least inducement for the ravenous host to halt. 



As flight is not consecutive day after day, but often im- 

 peded by bad weather, and as it is not continuously in one 

 direction, the average rate is not more than twenty miles 

 a day. It is also most variable, and at times reaches a 

 maximum of between two hundred and three hundred 

 miles daily. 



DIRECTION OF FLIGHT OF INVADING SWARMS. 



The wind is sometimes quite changeable during the 

 period of invasion, and we find the insects, at one time or 

 another, traveling in nearly all possible directions, except 

 due west. Yet the direction of the invading hosts has 

 been, and I believe always will be, conspicuously toward 

 the south and southeast. The exceptions are only sufficient 

 to prove the rule. 



WHEEB THE EGGS ARE LAID. 



The eggs may be laid in almost any kind of soil, but by • 

 preference they are laid in bare, sandy places, especially 

 on high, dry ground, which is tolerably compact and not 

 loose. It is generally stated that they are not laid in 

 meadows and pastures, and that hard road-tracks are pre*- 

 ferred ; in truth, however, meadows and pastures, where 



