THE LCCUSTS. 139 



end of the mass with the -same mucous matter, and then shuts up 

 the hole carefully. This mucous after hardening is only pervious 

 to water under frequent changes of temperature and during long 

 wet seasons. 



When severe frost comes the old die off rapidly and at the ap- 

 pearance of permanent cold weather they have all disappeared. 



Hatching. — It often happens that during the long dry autumns 

 of Nebraska, great numbers of the earlier laid eggs hatch out and 

 soon perish with the cold of winter. Many eggs also become 

 segmented in autumn and whether they survive till spring in a 

 healthy condition is still with many a disputed question. My own 

 opinion, derived from the closest observation, is that all such come 

 out in the spring, if they come out at all, in a sickly condition and 

 soon perish. Sometimes, too, as happened in 1877, there is much 

 warm weather in January and February, during which great num- 

 bers hatch out that invariably perish by the subsequent cold weather. 

 During spring the great hatching months are March and April. 

 In these months cold always interrupts the process. This occurred 

 in the Spring of 1877, when there were many cold days and chilly 

 winds, and as a consequence hatching was not over till early June. 



Departure of Locusts. — As already stated, a few days after the 

 last moult on favorable days they are disposed to migrate. No ex- 

 ception to this rule is known in the region of the plains. It is pos- 

 sible that where they are few in number in their native habitat they 

 do not always migrate, but even that is uncertain. In Nebraska, 

 Iowa, Dakota, Kansas and Missouri they are disposed to return to 

 their native regions. They therefore move mainly northward and 

 westward. Their instincts seem to force them to dryer and higher 

 regions, where they originated. Such was specially the case when 

 countless millions left the State in 1876. During 1877, the spring 

 of which was rainy, cold and chilly, the greater part of those that 

 hatched out soon perished, and the few that survived seemed sickly 

 and demoralized. These survivors first mainly moved northward, 

 and then moved southward, and finally were seen to move in all 

 directions; often two columns, one above the other, moving in op- 

 posite directions. The greater part of this season's product of lo- 

 custs evidently ran out, and perished by too long a stay in a region 

 unadapted to them. 



Destructiveness of Locusts. — When the migrating locusts make 

 their appearance in Nebraska, the cereal grains are already har- 



