80 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
to incorrect conclusions ; hence we have found it necessary, in dis- 
cussing points relating to migrations, to use some term that would 
distinguish these flights from what may be more properly termed true 
migrations. 
Strange as it may appear to those who have not carefully studied the 
characteristics and habits of our western locust that it should be possi- 
ble to distinguish a local from an invading swarm ; yet, as we have here- 
tofore stated, this may be done in almost every instance, even when 
moving in the same direction, and apparently from the same point. As 
an illustration of the use of the term, we call attention to the records of 
autumn flights of 1877 in Appendix XII of our former report. These 
were in nearly every instance, where south of Minnesota, from the north- 
west, yet, as was then pretty well known, and as since ascertained, those 
hatched in the temporary regions, most of which having flown north as 
far as Dakota again turned southward, being joined usually by those of 
the section where they again started southward. In some instances our 
data from local observers enabled us to designate the time and section 
when and where this change of course began. 
The data obtained for 1877 — which, as wfll be seen by reference to our 
former report, are very full — show that there is considerable difference in 
these local flights in the area from Dakota south to Texas and the area 
embracing Minnesota and Northern Iowa, the Coteau des Prairies form- 
ing the dividing line. In the former the flights were uniformly northward 
until in July, after which they were southward until in September, the 
turning point being somewhere in Dakota, after which there was but 
little flying either way, the locusts doubtless perishing after their flight 
southward, and generally without doing injury or depositing any eggs. 
On the other hand, there were, as will be seen by the following extract 
from Mr. Whitman's report, repeated flights to the northwest and south- 
east through Minnesota: 
To sum up ; July 1 the air was thick with locusts over a considerahle portion of the 
State. July 3 to 6 they moved across the State to the northwest, and turning at Mor- 
ris westward ; on July 8 to 10, crossed the State to the southeast-;. July 11 and 12, 
crossed the State to the northwest ; July 20 and 21, after the wind had heen blowing 
from the northwest for four days, they crossed the State agaiu to the southeast ; July 
28, after some flying to the northwest, crossed the southwestern corner of the State to 
the southeast ; August 2, crossed the State to the southeast in full force. To all ap- 
pearance the locusts have spent the greater part of their time in the air since July 10. 
In 1875 the local flights were not so marked as in 1877 ; in that year 
the return flights generally reached their destination — their native 
habitats in the permanent region — but in the latter year, on account of 
adverse winds or their diseased condition, which was very marked, they 
failed to accomplish the apparent object of their return flights, and hence 
became aimless wanderers, driven to and fro, the weaker dropping out 
and dying as they moved until all had disappeared. Our local reports 
are full of accounts of their dropping as swarms moved over. 
As heretofore stated, it is true that it is possible in almost every in- 
