630 REPORT UNITED STATES GEOLOGICAL SURVEY. 



the entire grasshopper had formed in the egg. The oscillotions between thawing and 

 freezing, wet and dry weather, seemed to have destroyed great numbers. The damage 

 done to the eggs was greatest in low grounds. In both these years, also the spring of 

 1875 and the present spring (1876), there were an exceptionally large number of eggs 

 in the ground. In digging over the spots where the most eggs seemed to be laid, the 

 number ranged between 100 and 15,000 to the square foot. Isolated spots could always 

 be found where the number was much greater. If, indeed, all would hatch out, no 

 green thing could ever escape. 



5. Among the curious things about their natural history is the following: Rainy days 

 in some way are connected with the rapid development, or at least appearance, of the 

 little red parasite, Asioma gryllaria. On June 1, 1875, the university grounds in Lin- 

 coln, Nebr., were covered with grasshojipers, and about two in a hundred contained 

 these parasites, located mostly under or near the wings. On that day and night it 

 rained, though it remained warm; Immediately after it cleared up the next day three 

 out of every four grasshoppers were full of these parasites. Twice I have known this 

 to occur. The cause or connection between the raiu and the development of these 

 parasites I have not ascertained. 



The power of adaptation to varying circumstances which this migratory grasshopper 

 seems to have is simply wonderful. Perhaps naturalists, in studying them, have been 

 overhasty in drawing conclusions from a narrow range of fiicts. As to myself, after 

 watching and experimenting for so long a time, I am not so sure that I understand 

 them as I was ten years ago. 



As an example of bow liigb the grasshoppers may fly and the enor- 

 mous number comprising a swarm, I quote the following statement from 

 the signal-service observer station at Fort Sully : 



June 15. [Direction of wind, as ascertained by the records: 6 a. m. to 7 a. m., north- 

 east; then east till 10 a. m. ; then south till 3 p. m. ; southeast remainder of day.] Sev- 

 eral days previous to this date had been hearing of the approach of locusts along the 

 line of telegraph from Omaha, upward, to northwest; and at 4 p. m. of the 14l.h the 

 operator at Fort Thompson (85 miles south, 25° cast from Fort Sully) reported their 

 advance flying northwest and northwardly. At noon a large cloud of the insects passed 

 over until night, when they were no longer visible. Roughly estimated, the swarm 

 may have been about 50 miles long, 25 wide, and one-quarter to one-half mile in height. 

 A hail-storm the following day may have dispersed them. 



June 23. [Direction of wand : 6 a. m., southeast ; 7 a. m., southeast ; 10 a. m., south- 

 east ; 2 and 3 p. m., east ; rest of the day cairn.] Large flights of locusts passing over 

 during the morning, going north and northwest, at an estimated elevation of about 50 

 feet to as high as they were visible with iield-glasses, possibly a mile ; none alightiug. 

 This swarm, as near as could be ascertained by telegraph at the time, came from the 

 Minnes'ita infested region, along the line of the Sioux City and Saint Paul Railroad, 

 in a continuous cloud, probably 1,000 miles long from east to west, and 500 miles from 

 north to south. How much farther north of this post unascertained, and not conjec- 

 tured. — (Riley's Eighth Report.) 



At Virginia (3ity, in Southwestern Montana, tbe weather-signal ob- 

 server states that " the locusts were thickest on July 20 and 21, giving 

 tbe sun a hazy appearance. These 'emigrant' locusts came from the 

 plains of Dakota, and were here, the largest bodies on the above- 

 mentioned days, at least half a mile in thickness, and, as I learn from 

 reliable authority, they presented an unbroken width of 20 miles, being 

 even more numerous on the wings than here near the center." 



In Indian Territory and Northern Texas they become winged, and 

 migrate during the second and third weeks of May. 



Habits of the young. — The Kocky Mountain locust casts its skin, or 

 molts, tive times after hatching. The figure (Fig. 4, Plate LXIl) from 

 Mr. Kiley's eighth report graphically illustrates the process of molting. 

 It should be borne in mind that the locust, like all grasshoppers, is born 

 without wings, and during this period is called the larva. Soon the 

 wings begin to grow, appearing as little pads (Fig. 4, a.) When these ap- 

 pear it is called a pupa, while the winged adult is the imago. When the 

 larva is about to molt, the skin, which had become too small for it, 

 splits open on the back of the head and thorax, and the larva with- 

 draws itself through the rent, the body at first soft and flabby. With 



