636 REPORT UNITED STATES GEOLOGICAL SURVEY. 



raer thai came fresh from tbe direction of the mountains, and by attaching their legs 

 by fine silk threads to a snmll spring balance, found that their physical strength was 

 from 25 to 50 per cent, greater than that of grasshoppers treated the same way that 

 were hatched in Nebraska or in States farther eastward or uorthward. The same re- 

 sult was reached by caging them, aud ascertaining how long they would live without 

 food, and also by vivisection. In some places, also, the eggs that were laid in diforent 

 years since 18G4 did not hatch out. The changes from extreme wet to dry, and from 

 cold to hot weather, or some other unknown causes, seem to sap their constitutional 

 vigor. Were it not for this, loug ere now these grasshoppers would, from their enor- 

 mous luimbers, have desolated the whole country as far east as the Atlantic. — Prof. 

 Samuel Aughey, of the University of Nebraska, in the Lincoln (Nebr.) Journal. 



I have observed hundreds of winged locusts fall to the ground during flight, either 

 already dead or soon dying. These, upon examination, have generally proved to con- 

 tain no parasites, and I judge that their death was in consequence of impaired strength;- 

 this second generation, raised in an unnatural climate, not eciualiug in vitality the 

 first generations, aud succumbing to the fatigue consequent upon extended flight. — 

 Prof. F. H. Snow, of Kansas State University, in Observer of Nature. 



This view is also held by Mr. Whitman, of Minnesota. 



Mr. Riley states that in Missouri "the specimens which hatched in 

 aud left our western counties last spring were, on an average, somewhat 

 darker and smaller than their parents." It thus appears that the Rocky 

 Mountain locust is affected like most other animals or plants when re- 

 moved from their proper geogTaphical limits; but a few insects, such as 

 the Colorado potato-beetle, &c., being able to withstand a change of 

 climate. As will be seen below, a variety of spretiis head is found in 

 ]Srorthern New England, Illinois, and the Pacific coast. Though born and 

 bred outside of the dry and elevated Rocky Mountain plains, are dwarfed 

 and prevented by moisture and various natural causes, such as the 

 presence of forests, &c., from increasing in large numbers and migrat- 

 ing. These dwarfed individuals are a climatic variety of C. spreliis^ which 

 has been named atJanis by Mr. Riley, who, however, believes that it is 

 a truly distinct species from C spretus. But from a careful study of 

 the geographical variations of a number of moths common to the Atlantic 

 and Pacific States as well as the Rocky Mountain region, I have found 

 that Rocky ^Mountain and usually Pacific coast specimens are larger and 

 with longer wings than eastern examples. 



(See my monograph of Phahenidce, Hayden's United States Geologi- 

 cal Survey, p. 584, 589.) 



It appears that the var. atJanis collected in Illinois was first exam- 

 ined by Mr. Uhler and named C. spretus, but as Mr. Thomas's specimens 

 of spretus came from the locust-area of the plains, and his description 

 applies to the genuine spretns, his name should be regarded as the 

 authority rather than Mr. Uhler, whose name was not accompanied by 

 a description, so far as I am aware. 



"It is somewhat strange," says Prof. 0. Thomas, in the zoology of 

 Lieutenant Wheeler's Survey, p. 89:i, "that the first specimen ever 

 examined and named should have been found in Southern Illinois by 

 the writer and sent to Professor Uhler, of Baltimore, about the year 

 1860, though previous to that time various scientific expeditions had 

 penetrated the western i)laius; yet it is but seldom seen in the section 

 where that specimen was obtained." It is not impossible that the few 

 specimens of C. spretus said to have been seen east of the Mississippi 

 have flown over from the eastern limits of the locust-area in Minnesotii, 

 Iowa, or Nebraska, and that it is not a permanent resident, just as the 

 Asiatic migratory locust occurs temporarily in England and Sweden. 

 The variety called by Mr. Riley C. atlanis is, however, common in Illi- 

 nois, and extends west to central Missouri. This is a smaller form, with 

 shorter wings, and markings more like the eastern locust, but difiering 

 decidedly in the notched end of the hind body of the male. There is 



