18 
PLANT-BUGS INJURIOUS TO COTTON BOLLS. 
this Bureau. a That this abnormal growth may be caused by the 
punctures of Heteropterous insects was first pointed out by the author 
in his report of preliminary investigations of the conchuela. 6 Since 
then, in the course of more extended investigations of this and other 
Heteropterous cotton pests, incidental observations on this point 
have been made by the writer, a summary of which will be found in 
a publication by Dr. W. E. Hinds dealing with the relation of the 
proliferation to the cotton boll weevil. c When caused by the boll 
weevil, this growth can be easily distinguished from that caused by 
Heteropterous insects by the distinct open puncture which extends 
through from the outside of the carpel. The entire inner side of the 
carpels of bolls damaged by plant-bugs is frequently found on exami- 
nation to present a rough or papulous surface due to the fact that the 
punctures are so close to one another that the proliferous growths 
merge together. At Tlahualilo, Durango, Mex., on July 17, 1905, an 
examination of 100 injured bolls revealing over 4,000 punctures 
by plant-bugs (practically all by Pentatoma ligata) developed the fact 
that 34 per cent of the punctures had resulted in proliferation. 
On November 1, 1905, an examination of 25 bolls at Dallas, Tex., 
from a field where three species of Pentatomidse (Nezara hilaris, 
Euschistus servus, and Thyanta custator) occurred in considerable 
numbers, gave the following results in regard to proliferation, using 
the lock as the unit: 
Table II. — Proliferation on mside of carpels rf locks fed upon by Pentatomids. 
Size of 
bolls 
(diameter). 
Locks. 
Number. 
Number Per cent 
showing 1 showing 
prolifera- prolifera- 
tion, tion. 
Destroyed 
by plant- 
bugs. 
Slightly 
injured. 
Unin- 
jured. 
Inches, 
i-i 
1-1* 
Total 
60 
40 
42 70 
11 27 
39 
8 
3 
3 

a2 
100 
53 
47 
6 
2 
a Inside carpels showing three and four punctures, respectively— no apparent injury. 
The objective point of the attack by insects investigated is the 
seed, which they are able to reach with little difficulty by means of 
the threadlike organs of their mouth-parts, except in large, nearly 
mature bolls which are protected by the resistance offered by the lint. 
Except in the larger sized bolls, therefore, a blisterlike spot or prolif- 
a Bul. 51, Bur. Ent., U. S. Dept. Agr., 1905. 
6 Bul. 54, Bur. Ent,, U. S. Dept. Agr., p. 29, 1905. 
c Bul. 59, Bur. Ent., U. S. Dept. Agr., p. 29, 1906. 
