NATURE OF INJURY. 17 
relationship in that they occur with greater frequency on bolls injured 
by plant-bugs than on those entirely free from injury from this source. 
Although no external discoloration in the form of spotting of the 
bolls is known to result directly from the attacks of the representa- 
tives of the Heteropterous families thus far studied, and included in 
this discussion, there is frequently present more or less reliable 
external evidence of damage. Bolls when severely attacked by plant- 
bugs may flare, turn yellowish, become flaccid, and finally fall to the 
ground. This has been observed to take place in bolls as large as 
1J inches in diameter, although it more often occurs in bolls which 
have attained less than one-half of the normal mature size than in 
larger bolls. Occasionally a deformity results from the destruction 
of one lock when the boll is quite small, but this frequently occurs 
when there is no evidence to connect the deformity with plant-bugs. 
In addition to these physical changes in the boll, it has been observed 
with several of the plant-bugs that damaged bolls may be detected in 
many cases by the yellowish stain produced on the bracts and carpels 
by the liquid excrement. 
INTERNAL APPEARANCE OF BOLLS DAMAGED BY PLANT-BUGS. 
Description. — Plant-bug injury to cotton bolls can be positively 
determined only by means of an internal examination. This subject 
was treated in the author's report of preliminary investigation of 
the conchuela in northern Mexico, but additional observations allow 
of a more complete consideration at this time. While these observa- 
tions are for the most part based on the conchuela, it has been found 
that the same effects result from the attacks of the other representa- 
tives of the Pentatomidae, as well as the representatives of Coreidse 
and Pyrrhocoridse upon which studies have been made. The most 
essential factor in determining injury to cotton bolls by these plant- 
bugs is the appearance of the inner side of the carpels (PL II. fig. 7), 
where the point of entrance of the insect's seta^ is marked by a minute 
dark spot surrounded by a watery or blisterlike, bright-green area, 
contrasting distinctly with the light, dull-greenish background. In 
many cases, particularly in bolls three-quarters grown or more, these 
blisterlike areas increase to a diameter of 4 or 5 millimeters, but in 
other cases, more especially in small, rapidly growing bolls, a physio- 
Logical reaction in the form of a proliferation of plant tissue takes 
place. This proliferation (PI. Ill, figs. 6-8) is of the same nature as 
that which results from the puncturing o( the carpels o{ the bolls bv 
boll weevils, described by Hunter and Hinds in a previous bulletin of 
o Bui. 51, Bur. Ent., U. 8. Dept. Agr., pp. 29-30, L905. 
22348— Bull. 86—10 2 
