26 BULLETIN 918, IT. S. DEPARTMENT OF AGRICULTURE. 
The data in the foregoing table were compiled from records kept 
of weekly examinations made of 100 boll (green) samples taken from 
different plantations in the Laguna district. The bolls in each sample 
were taken by walking through the same fields each week and pick- 
ing the bolls at random. 
ESTIMATE OF DAMAGE TO LAGUNA CROP, 1919. 
In making an estimate of the damage caused by P. gossypieUa to 
the cotton crop of the Laguna for 1919, it was thought best to select 
certain average fields on average plantations and to keep these 
particular fields under close surveillance during the entire year. 
Through the courtesy of Don Carlos Gonzales y Farino, of Torreon 
and of the Tlahualilo Company, Tlahualilo, Durango, certain fields 
upon their properties were selected. These fields were chosen with 
the utmost care in order to obtain as nearly as possible an average 
of all conditions of the Laguna, with respect to factors controlling 
the amount of damage caused by P. gossypiella. Other fields in dif- 
ferent parts of the Laguna were examined as often as time would 
permit for comparison with these fields. Each of these fields was 
visited regularly (as far as conditions would permit) once a week, 
and samples of 100 green bolls taken, so that the rate of increase of 
infestation might be ascertained. 
Samples of seed cotton were also taken at the beginning of each 
pick from each of the experimental fields, to determine the damage 
caused by the pink bollworm in the different harvesting periods. 
These samples were ginned in a sample gin separately, accurate 
weights being kept of the quantity of lint and seed. A sample of lint 
from each field sample was taken for classification by the Bureau of 
Markets, United States Department of Agriculture, to determine 
the discolorations, grades, and spinning qualities of the lint. 
A 2-pound sample of seed was taken from each field sample for 
chemical analysis to determine quality and quantity of oil. 
DAMAGE TO SQUARES AND BLOOMS. 
The pink bollworms enter the squares just after hatching from 
the eggs, and continue feeding until they complete the larval stage, 
notwithstanding the fact that the squares may bloom in the mean- 
time. Larvae of all stages have been found in the squares, but 
generally speaking only full-grown larvae have been observed in the 
blooms. To ascertain to what extent this floral feeding habit tended 
to cause damage the following experiment was carried on. 
Tags were placed on 343 normal blooms and on 343 infested blooms 
during June and July. Table XII shows the results. 
