50 
PLANT-BUGS INJURIOUS TO COTTON BOLLS. 
cotton when the bolls became more numerous and large enough to 
be attractive to them. 
The most thorough study of the changes in the numerical status of 
the conchuelas during July, 1905, was made in a tdbla comprising 
about 120 acres and known as "Ceceda A 14" (fig. 7). The cotton 
in this tabla was zoca or seppa, and during the first half of July repre- 
Fig. 7.— Diagram of a portion of the Tlahualilo Cotton Estates. The shaded tablas are the principal ones 
referred to in the text. (Original.) 
sented conditions more attractive to the insects than did any equal 
area of planta (planted) cotton. Five examinations were made during 
July near the west end of this tabla, beginning with a row about 1 5 or 
20 yards from the end and examining across the tabla, changing to 
next row east, every 10 plants. The results of this examination are 
summarized in the following table : 
Table XXI. — Variation in abundance of Pentatomids during July, 1905, at Tlahualilo, 
Durango, Mexico. 
When examined. 
Number of 
plants 
per row. 
Number of 
infested 
plants 
in 100. 
Adults per 100 plants. 
Total adult 
Pentato- 
mids per 
100 plants. 
Number of 
nvmphs P. 
P. ligata. 
P. sayi. 
Thyantasp. 
ligata per 
100 plants. a 
1905. 
July 11 
100 
99 
98 
103 
96 
19 
30 
31 
12 
52 
52 
59 
33 

3 
4 
n 

2 

52 
57 
113 

15... 
is i< 
21... 
2< 
27 . 
n 33 

29 
17 fl 17 
1 2 l 5 
Total 
Average 
493 
98.6 
99 
19.8 
213 
42.6 
1.4 
2 222 
.4 44. 2 
6 
1.2 
Small figures indicate the instars. 
