98 
GENERATIONS OF THE BOLLWORM. 
It has long been stated that the number of generations annually of the 
bollworm in the cotton belt varies from about four in the more north- 
ern part to six or even seven in the extreme southern part. It does 
not appear, however, that this statement is based on actual breeding- 
experiments, but rather on the result of field observations. Conclu- 
sions regarding this matter based solely on field observations are some- 
what unsatisfactory, as they are apt to be spread over a wide terri- 
tory and to be complicated by variations in climate and environment, 
as well as by the fact that the broods are confused on account of the 
long period of emergence of the moths in the spring. This causes the 
period of spring oviposition to be lengthened, so that long after the 
majority of bollworms are well grown others are still in the egg 
stage. These supplementary generations persist thi'oughout the sea- 
son, and, although numerically unimportant, are apt to lead to con- 
fusion regarding the principal ones. 
As the question of the number of generations is one of importance, 
effort has been made to secure as much data on the subject, confirma- 
tory or otherwise, as possible. In 1903 attempt was made to secure 
information on this point by ascertaining, for different localities of 
the cotton belt, the periods of maximum oviposition of the moths 
during the season. It was thought that these egg records for the 
season, when plotted, would indicate approximately the periods of 
greatest abundance of the moths, thus marking the respective genera- 
tions. Theoretically such data would undoubtedly furnish the infor- 
mation desired, but in practice many factors were found to enter into 
the making of trustworthy records, such as variations in the age of 
the corn used in making counts, the character of the weather, etc. , so 
that little may be safely inferred from the egg records obtained. It 
is proper, however, that acknowledgment be here made of the assist- 
ance received in_this work from Dr. W. E. Shaw and Mr. A. C. Lewis, 
of the Oklahoma Agricultural Experiment Station: Mr. Mark Eiegel. 
Pomona. Ga.: Prof. H. A. Gossard, of the Florida Agricultural 
Experiment Station, and the late Mr. G. H. Harris, of this Department. 
The records made by Mr. Eiegel and by Mr. Harris are presented 
under the caption •'Oviposition on corn" (p. 42), to which the reader 
is referred. 
At the beginning of the season of 1904 it was decided to carry a 
series of consecutive generations through the entire summer under 
natural field conditions. This work was conducted in a large field 
cage placed in a lot adjoining the laboratory at Paris. Tex. The cage 
consisted of a solid framework 15 feet long. 12 feet wide, and 8 feet 
high, covered with ordinary black window screen and provided with a 
small door on the side. (See PL XVII.) In it were planted two lots 
