12 



own hatching. I believe it is not as yet fully known what con- 

 nection there may be between the migrations of the locust and its 

 season of egg-laying, but it seems that some cause for the fact 

 that portions of our swarms remain here to breed can be found 

 in an early stage of egg-laying. Here again we have a difference 

 between our own broods, and not only the new swarms that come in 

 upon us from the mountain regions, but also those which leave the 

 more southerly regions and fly to the northwest on acquiring 

 wings. As for the latter, in the flight from the Missouri Valley 

 northward in 1875, Prof. Riley was able to learn of no case of 

 their depositing eggs, nor were the hatching grounds, (outside of 

 Minnesota,) of last spring found to be anywhere in the vicinity 

 of those of 1875; as for the swarms that have descended upon us 

 during the summer, I have not been able to learn of any deposit 

 of eggs whatever in any of their stopping places on their way 

 toward this state, and even on arriving here it was evident in 

 most cases that they had not }'et reached the season of egg-laying. 

 Between the 17th and the 31st of July there was a gradual move- 

 ment, apparently of new-comerg, across the state towards Iowa, 

 and the egg-laying did not become general until about the latter 

 date. Between the first and sixth of August other swarms came 

 in, and these again in most cases did not begin to lay until a 

 week or more after their arrival. Still others came in later, and 

 the laying was kept up until late in September and was seen to 

 occur in October, or as long as the locust remained alive. On 

 the other hand our own stock were seen in 1875 to be laying 

 within eight days after their flight commenced and in the places 

 where they first alighted, and during the past season the laying 

 had already begun on the third of July and by the tenth had 

 become general in the western part of Nicollet county, within a 

 few miles from their hatching-ground, and within two weeks 

 from the time when the flying began. This early period of lay- 

 ing may be of itself a sufficient cause for portions of our swarms 

 remaining here, while the less mature pass on. 



NATURAL DECREASE FROM ONE YEAK TO ANOTHER. 



But though portions remain, there is no increase in their num- 

 bers from one year to another. So far from holding its own, the 

 locust has seen its breeding grounds decrease from nearly fourteen 

 counties in 1873, to some seven and a half counties in 1874, and 

 about five and a half counties in 1875; and in this latter area 

 though able to inflict serious damage in many places (owing chiefly 



