BIOLOGY OF THE MEXICAN COTTON BOLL WEEVIL. 5 
(fig. 7). The field hatchery consisted merely of a certain area in 
the cotton field about 20 feet square. The infested squares were 
placed in the hatchery beneath the cotton plants in the natural posi- 
tion of fallen squares. After 15 days from the date of egg puncture 
the infested squares were placed in small wire-screen hatching cages 
(fig. 7). The hatching cages were constructed of 16-inesh wire 
without bottoms and protected the infested squares in such a manner 
that the squares received about the same amount of sunshine and 
moisture as under normal field conditions. Maximum and minimum 
thermometers were installed in the field hatchery (fig. 9). Both in- 
struments were resting on the soil in order that the exact minimum 
and maximum temperatures to which the developing weevil was 
subjected under field conditions might be determined. 
Ten hibernated male and female weevils were used to secure the 
developmental period of the first generation of weevils on upland 
cotton. In addition, 10 hibernated female weevils that had not been 
fertilized were used to determine the effect of nonfertilization after 
emergence from hibernation on the progeny produced. When the 
first generation weevils became adults 10 pairs were selected and used 
for securing the fecundity records on upland, long staple, and sea- 
island cottons. The fecundity records for the second generation on 
upland cotton were secured in a like manner. After the 15th of 
August, however, the weevils had developed so rapidly in the field 
that it was necessary to discontinue the study of the developmental 
period of the weevil for each successive generation. 
For securing the effect of the lower fall temperatures on the de- 
velopmental period of the weevil, upland cotton plants were stripped 
of all cotton squares and then caged. As soon as the plants grew 
new squares female weevils were placed in the cages for oviposition 
purposes. About every 20 days a new series of developmental studies 
was inaugurated. This process was continued until frost killed the 
cotton plants in late fall. 
FOOD PLANTS OF THE BOLL WEEVIL. 
Owing to the economic importance of the question as to whether 
or not the boll weevil can adapt itself to plants other than cotton for 
food, this phase of the life history has been carefully studied in 
practically every section of the cotton belt. 
The boll weevil has as regular food plants the cultivated cottons 
of the United States, Mexico, Cuba, and Central America, and certain 
wild cottons, including Gossypium davidsoni on the coast of the 
Gulf of California, and also the so-called wild cotton, T’hurberia 
thespesioides, in Mexico and Arizona. 
