76 
BULLETIN 1476, U. S. DEPARTMENT OF AGRICULTURE 
The possible presence of geographic races: The manner of con- 
ducting experiments to determine this point was the transfer of 
material from one locality to the other, that is, from a one-genera- 
tion locality to a two-generation locality, and vice versa, subse- 
quently breeding the offspring for several years to observe their 
reactions to change in environment. 
During the winter of 1920-21 a series of overwintering larvae 
were transferred from western New York to the Massachusetts 
area, and the progeny of this material have been carried through 
their entire seasonal development since that time in large field cages. 
A similar cage was used as a check in which native Massachusetts 
material has been reared under similar conditions, and the results 
from each lot of material checked by insectary rearings. The re- 
sults during the first four years are shown in Table 22. 
Table 22. — Results of rearing Pyrausta nubilcilis material transferred from 
western New York to Massachusetts during winter of 1920-21 
Number 
of gener- 
ations in 
original 
locality 
Number of generations in Massachusetts 
Source of material 
1921 
1922 
1923 
1924 
Silver Creek, N. Y. (environs) _ 
1 
2 
1 
9 
1 
2 
1 
.0) 
1 
2 2 
1 1 complete, 2 partial. 
2 A second flight of moths was observed in this cage in 1924, but no dissections were made to determine 
the percentage of the second generation which developed. 
Similar rearings were carried on at Silver Creek, N. Y., during 
the period 1921 to 1924 with two-generation material transferred 
from Massachusetts in the early spring of 1921. Under these condi- 
tions the Massachusetts material adhered to its two-generation sea- 
sonal development for this four-year period. 
These experiments must be continued for a period of several years 
before any conclusions can be reached as to the effect that climatic 
factors may have in changing the number of generations through 
which the insect may pass in completing its seasonal development. 
The time of year when the material is transferred, and the method 
of handling after its arrival, as well as conditions under which the 
experiment is conducted, undoubtedly exert an influence during at 
least the first year or two of the experiment. 
Climatic conditions : In the past, temperature, since it is con- 
ceded to be one of the most important stimuli for biological develop- 
ment, has been given great weight in the solution of many parallel 
problems. 
A detailed study of the variation of climatic factors upon the 
seasonal history of this* insect includes a course of experiments 
covering the study of the effects of the important climatic factors. 
The study of temperature consists of temperature work, carried on 
in incubators, where a constant temperature of great accuracy can 
be maintained, with the humidity conditions fairly uniform. The 
results of these experiments, in connection with important infor- 
mation obtained from the study of the behavior of the insect under 
field and insectary conditions, will be used when the data obtained 
