178 THE BOOK OP WHEAT 



East of this territory was a frequently invaded strip about five 

 degrees in width. A great scope of territory farther east, 

 south and west was periodically visited when the natural con- 

 ditions on the permanent breeding grounds were such as to 

 produce myriads of grasshoppers. They could live only one 

 generation on the lower lands, and then perished. Large por- 

 tions of their grounds are now cultivated, and this restricts 

 their multiplication. It is thus perhaps impossible for such 

 overwhelming swarms to occur as formerly. Such swarms as 

 do occasionally appear are more localized, and not of such un- 

 controllable magnitude. They may still be relatively abund- 

 ant, however. During 1901 in Canada, several hundred insects 

 could be seen "to the yard," and "dead locusts could be 

 gathered up in wagon loads and at times be smelt for half a 

 mile," after poison had been used. In Montana they fre- 

 quently devastate ranges so that the herds must seek pasture 

 elsewhere. 



The Eocky Mountain Locust lays its eggs in almost any kind 

 of soil, preferably in bare, sandy places on high and dry ground. 

 They are laid chiefly in the first inch of soil, and in masses or 

 pods surrounded by a mucous fluid, each pod containing about 

 30 eggs. The average laying season extends over 6 to 10 weeks, 

 and about 3 egg masses are formed by each female. The time of 

 hatching depends entirely on the climate and latitude. While 

 the young locust is very active, it will remain almost stationary 



if food is plenty. The migrating 

 propensity is developed only after 

 the first molt, and frequently not 

 until after the second or third. 



I When food becomes scarce the lo- 

 custs migrate, often in a body a mile 

 wide. From the very first they con- 

 ROCKY MOUNTAIN GRASS- S re S ate an <* display gregarious in- 

 HOPPER; a, PUPA; b, FULL stmcts ' The y feed as the y advance, 

 GROWN LARVA; c, YOUNG devounn S everything in their path. 



LARVA. NATURAL SIZE. If ^ ar6 num erOUS enough to 



devastate a region, they are forced 



lo feed upon one another, and immense numbers perish 

 from debility and starvation. They usually move only 

 during the warmer hours of the day, and in no particular 



