82 



previous summer and fall. It also appears to be pretty well ascertained 

 that the spring brood, hatched in the Mississippi valley, never does much 

 injury after it commences flying, and produces no further broods. 



The following are extracts from a letter written by Mr. Byers, of Den- 

 ver, Colorado, in answer to some inquiries on this subject : 



Question. When the swarms (flyiug) appear in that immediate section, where do they 

 usually come from? 



Answer. From some point between north and west, usually about north 30^- west. 

 The most destructive flight we ever had here was in 1864. Early iu the sejuson we heard 

 of great swarms of grasshoppers hatching out upon the jdaius of Montana, in the valloy.s 

 of the Three Forks of the Missouri River, and along the Yellowstone. Later we heard of 

 their progress south and east. August 21st they commenced coming into the St[Vrain 

 caiion or valley, about fifty miles north of Denver ; about five days afterward the 

 swarm reached Denver, darkening the sky and often covering the streets. They 

 devoured corn, tomatoes, potato-vines, onions, «fcc., almost entirely, and within the 

 space of five days. The column moved on at about the rate of ten miles per day, 

 and left the (tlieu) settled portions of Colorado within the valley of the Arkansas. We 

 heard nothing more of them. 



But myriads remained or continued arriving from the north and west, and deposited 

 their eggs in plowed fields and upon rolling, sandy, and gravelly land, where the soil 

 was unbroken. In September and October most of them died. Iu March following 

 the eggs deposited by them began to hatch, first upon the sandy and gravelly hill-sides 

 facing the sun, and, somewhat later, iu the fields and colder soils, continuing to appear 

 until late iu May. Where numerous, they literally devoured every green thing. If a 

 wheat-field (in which none were hatched) was attacked, they moved across it, or from 

 the circumference to the center, with the regularity and effect of advancing flames. 

 The swarms of 1864 destroyed com and other late crops : the young of 1865 ate up 

 wheat and other .small grains. The comparative damage was probably as one to four, 

 the young brood being far the most destructive. 



Mr. Byers, in answer to the request to describe their method of flight, 

 and to state what relation it bears to the wind, says : 



Generally they move leisurely, the direction of their flight being influenced largely 

 by the direction of the wiud. In fact I attribute their general course mainly to the 

 prevaling winds, which come at that season, almost iuvarialdy from the northwest. 

 Toward noon, in bright warm days, they rise by circular flights, each seeming to act 

 iudividually. When they have reached a considerable height they sail away, with tol- 

 erable regularity, in one direction. If there is no wind, many of them continue whirl- 

 iug about iu the air, but away beyond, myriads can be seen moving across the sun 

 toward the southeast, looking like snow-flakes. If there is a change in the atmo- 

 sphere, such as the approach of a thunder storm or gale of wind, they come down pre- 

 cipitately, seeming to fold their wings and fall by force of gravity. If not interrujjted 

 by such causes they descend during the afternoon. The swarm of 18f54 and brood of 

 1865 are the only general visitations that have scourged Colorado. Similar ones — both 

 flights and broods — have visited portions of the Territory each year since, but gener- 

 ally confined to particular localities or narrow belts. The swarms that invaded Kan- 

 sas and portions of western Iowa in 1867 were traced from their hatching grounds in 

 western Dakota and Montana, along the east flank of the Rocky Mountains, and in the 

 valleys and plains of the Black Hills, and between them and the main Rocky range. 

 In 1852 I first observed this insect in the valley of the South Fork of the Columbia, not 

 far from Fort Hall. A swarm, lasting two or thi'ee days, passed over from about west- 

 southwest, moving with the wind, at times darkening the sun, covering horses, cattle, 

 and wagons, against which they were driven. The Digger and Snake Indians gathered 

 them for food. In 1865, those of the spring brood which were not ijijured by fly 

 which attacked them, as soon as their wings were sufficiently develoiied, took to 

 flight and we lost trace of them on the plains. The same year, in the latter part 

 •of August, in the valley of South Boulder, close up to the Snowy range, I found 

 young grasshoppers very numerous, varying in size from those just hatched out to 

 those one-third grown. I know that winter caught and killed these before they were 

 able to fly. Late in 1867 the Middle Park was invaded by a swarm which came from 

 the northwest, and deposited their eggs there. In 1868 those eggs began to hatch, in 

 the lowest and warmest portions of the Park, in June, increasing in July, and continu- 

 ing to hatch through August in the higher portions of the Park, near the snow-rijn. 

 Those hatched first moved from their native place up the Park eastward, but never 

 got out of it. The later broods never left their hatching ground. All were destroyed by 

 the fall snows. From the middle to the 25th of August, 1868, I was on and near the 

 Snowy range, east of Middle Park. There was during this time a large daily flight of 

 grasshoppers from about west-northwest, reaching apparently to the highest limit of 

 Tision, even to those standing on the highest peaks. Daily, showers of rain, snow, and 



