EELATION TO AGRICULTURE 31 



different from grasshoppers will congregate by 

 the hundred and gorge themselves until scarcely 

 capable of flight when those insects appear. Her- 

 ons forsake their marshes, vultures their carrion, 

 seed-eaters their seeds, and ducks their wild 

 celery, when an extraordinary host of grasshop- 

 pers is sighted. Such an event has happened not 

 once but a score of times in the history of the 

 United States; it is common in Africa and other 

 locust-infested lands. The reports of the State 

 departments of agriculture are replete with such 

 instances. 



About fifty years ago the settlers near Great 

 Salt Lake were reduced to starvation rations 

 through the destruction of their freshly planted 

 crops by swarms of grasshoppers. Then came 

 the guUs. True to their instinct, they gathered 

 from the lake in thousands, and before many days 

 had passed the locusts were no more ; all had been 

 devoured. There stands to-day in iSalt Lake City 

 a beautiful monument erected in honor of those 

 gulls. 



The destruction, however, of suddenly arising 

 insect swarms, though important, is not the chief 

 function of birds in the sphere of agricultural 

 economy. Their mission is to exert a steady pres- 

 sure on insects as a whole, to act as "moppers 

 up" for the predaceous species, and at the same 

 time to keep the latter from spreading beyond 

 control. 



