128 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
Variations between months of consecutive years — Continued. 
Tears and stations. 
VIRGDHA CITY. 
1872- '73 
1873- 74 
1874- 75 
1875- 76 , 
1876- 77 
1877- 78 
OMAHA. 
1872- 73 
1873- 74 
1874- 75 
1875- 76 
1876- 77 
1877- 78 
December. 
18.8 
16. 7 
24.9 
30.5 
24.4 
24.0 
19.0 
25.2 
2a 4 
33.5 
19.2 
39.2 
January. 
23.4 
23. 1 
1.7 
17.1 
18.8 
23.1 
16.9 
22.3 
16. 1 
26.8 
20.2 
28.9 
February. 
15.6 
18.4 
22.8 
28.1 
27.5 
27.9 
26.9 
23.4 
13.8 
30.1 
37.3 
36.9 
Mean. 
19.3 
19.2 
19.8 
25.2 
23.6 
25.0 
20.9 
23.6 
19.4 
30. 1 
25.6 
35.0 
It will be seen by comparing these means that as a very general rule 
the temperature was higher in the winters of 1873-74 and 1875-76 
than the preceding or following winters, but that to this rule the winter 
of 1877-78 forms a remarkable exception. But in these cases the win- 
ters appear to correspond with the general character of the year. The 
results are scarcely sufficiently marked and uniform to justify the con- 
clusion that they present a clew to the solution of the problem. 
An inspection of the summer months in Table VI shows a much 
smaller variation ; for example, at Breckenridge, where the differences 
between the winter means are the greatest, the summer means are as 
follows: 1873,520.2; 1874, 53°. 4; 1875, 51°.0; 1876, 52°.6; 1877, 52°.6; 
the extreme variation being but 2°.4. 
Yankton : 
1874 65 c .2 
1875 61°.4 
1876 62C.9 
1877 63°.l 
Virginia City : 
1874 53C.& 
1875 53^.6 
1876 530.0 
1877 52°.6 
A longer series of years would doubtless show greater variations, but 
if these furnish any indication of the general rule, it is evident the 
means of summer temperature furnish no such differences as woidd 
seem to be required for such important results. So far, then, as the 
records of temperature thus far examined are concerned, neither the an- 
nual nor the monthly means show any important fact to sustain the 
assumption that unusual heat is one of the conditions necessary to the 
excessive development of the locusts. If they show any important fact 
bearing upon the subject, it is that the winter season (including March) 
has more to do with their development than the temperature of the sum- 
mer season. 
