620 REPORT UNITED STATES GEOLOGICAL SURVEY. 



progeny of these spread northward in 1874, but while fresh swarms 

 entered the State in 1874 from the northwest, they did not, probably, 

 add much to the stock of eggs deposited by the Minnesota brood, and 

 Mr. Whitman thinks it " probable that the locusts which hatched in 

 Minnesota last spring were, to a considerable extent, the descendants 

 of the swarms which entered the State in 1873," 



Mr. Whitman believes that in Minnesota there is not a return-flight 

 of freshly-fledged locusts toward the Eocky Mountains, as shown by Mr. 

 Riley and others to take place in Nebraska, Kansas, and Missouri. On 

 the contrary, " the wind which sweep clear away the hatching-swarms 

 of the more southern States carry our own but a few miles from their 

 birthplace." He seems to incline to the belief 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. While those observed late in summer 

 to fly northwestward did not lay eggs, " on the other hand our own 

 (Minnesota) 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 3d of 

 July, and by the 10th 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 laying 

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

 here, while the less mature pass on." 



From one year to another Mr. Whitman has noticed a natural de- 

 crease in the number of locusts breeding in Minnesota : 



Numbers of locusts have hatched out and have died without reproducing them- 

 selves. In this connection, the State of Minnesota has an advantage over more 

 southerly regions, in the fact that we are situated nearer to the breeding-grounds of 

 invading swarms. Of these, the earlier comers are more likely to pass over ua before 

 reaching the full period of their development, while the later comers are cut oft by 

 our earlier frosts; and of the eggs which are left with us, being deposited earlier iu 

 the season, more are likely to hatch in the fall and become harmless. On the other 

 hand, the invaders are more likely to mass their forces in more southerly States, reach 

 them in full maturity, and remain later in the season, while the eggs, being deposited 

 later than ours, remain mostly unhatched until spring. These considerations enable 

 us to understand why certain counties iu Missouri, where the locnst hatched in 1875. 

 presented in May such a picture of devastation and desolation as Minnesota has never 

 seen in all its locust experience. 



The locust has also become shorter lived, and many were killed by 

 the Tachina maggot, while of the invading swarms of the present year 

 "large numbers of the bodies of the dead could be found in the fields 

 early in September," and " large numbers remained alive until they 

 were killed by frost, and even then died with eggs unlaid." Another 

 effect of naturalization during the last four years, says Mr. Whitman, is 

 that "while it has lost some portion of its inclination or its ability to 

 migrate, it has also lost somewhat of its gregarious character." Indeed, 

 had it not been for tbe new-comers in 1876, " next year would have seen 

 the insects so few and so scattered as to be incapable of great damage, 

 and they might become in a year or two as flitting and as unnoticeable 

 as the red legged locust that breeds with us every year." Mr. Whitman 

 adds that, " in regard to changes in color and appearance, while the 

 locusts which hatched iu Minnesota last spring had when fully devel- 

 oped something of the darkness and dullness of old age, the brightness 

 and fierceness of the fresh invaders was apparent to every one." Mr. 

 Whitman concludes, and we think the facts reported by him bear out 

 his statement: " Nothing is more certain than that we might, by gen- 

 eral and continued eflbrt, practically eradicate the offspring of almost 

 any one year's invasion; nothing is more probable than that iu almost 



