236 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



however, they do not travel every day ; and where food is abundant 

 they scarcely travel at all." 



Moreover, as we have jnst shown, the migratory propensity is seldom 

 manifested during the first or second larval stages, and it is, in fact, 

 largely dependent on conditions of health and vigor of the insects, and 

 on tfie amount of food supply. We have learned of no cases where the 

 young have extended, during growth, ten miles east of the hatching 

 limit. 



As we shall presently show — and the fact is more fully brought out 

 in Chapter VI — the insects, when they get wings in the Temporary re- 

 gion, especially in early summer, instinctively fly to the north or north- 

 west, and do not extend to do damage farther east. Those, also, which 

 acquire wings later in the summer in more northerly regions, and which 

 fly more to the south, never extend any great distance east of where 

 they hatch; those developing on the eastern eonfines of the species' 

 range (Map I), passing south westwardly, and those born toward the 

 mountains southeastwardly. In 1875, a few stragglers were carried as 

 far as the center of Missouri by being swept into the Missouri Eiver, 

 and drifting on logs and chips during the annual rise in July. But 

 whenever scattering individuals are carried in this or any other way 

 beyond the eastern limits we have laid down, they soon perish. Most 

 of them are diseased or disabled, and if they lay eggs, these hatch in the 

 autumn and perish at the approach of winter. 



NOT LED BY "KINGS" OR "QUEENS." 



"The idea that the young locusts are led in their marches by so-called 

 -t kings' or 'queens' has been at different times very prevelent. It is, 

 however, quite unfounded. Certain large locusts, belonging to the 

 genera Acridium and CEdipoda, hibernate in the full-grown, winged 

 state, and not in the egg state, like the Rocky Mountain species. Always 

 with us, their presence is simply more manifest in the spring, when the 

 face of the earth is bare. Hopping with the others or falling into ditches 

 with them, they give rise to this false notion, and it is an interesting 

 fact, as showing how the same circumstances at times give rise to sim- 

 ilar erroneous ideas in widely separate parts of the world, that the same 

 idea prevails in parts of Europe and Asia. 



Fig. 6.— American Aceidium. (After Riley.) 



