NATURE OF INJURY. 19 



eration on the inner side of the carpel, such as has been described, 

 indicates an injury to the seed or discoloration of the lint directly 

 opposite. When a seed of a rapidly growing boll is fed upon at first 

 the stimulation, probably partly mechanical and partly due to salivary 

 fluids of the bug, causes an increase in the flow of sap to the injured 

 seed, causing a characteristic watery appearance. The seed after- 

 wards gradually becomes discolored (PL II, figs. 4,6) and proliferous 

 tissue is extruded from it in some cases. Punctures near the tip of 

 the lock are most effective in destructiveness ; in one case (PI. Ill, 

 fig. 8) 4, 6, 16, and 10 punctures per lock, respectively, were found to 

 have produced proliferation from the seed nearest the tip of the boll 

 in each lock and would have prevented the opening out of the cotton 

 if it had been allowed to mature. This is equivalent to complete 

 destruction of the boll. The lint surrounding the point where the 

 insect's mouth-parts enter turns yellowish, and, if the injury is severe, 

 finally becomes a dirty brown and decays (PI. II, figs. 1, 2; PI. 

 Ill, figs. 1-8), which probably is the condition Glover referred to as 

 *'the rot." 



As the great majority of the punctures are made on the outer half 

 of the bolls, it is there that staining is most frequently found. 



In general bolls damaged by plant-bugs when open (PI. Ill, figs. 

 1-5; PI. IV) are characterized by shriveled locks and only partial 

 spreading of the carpels. The entire lock may become a brownish 

 shriveled mass or the shriveling may be confined to the outer tip. 

 Again, locks may be perfect except for a small stained patch of lint, 

 which, however, might offset the value of the unstained product. 

 Seeds in nearly mature bolls may be destroyed without the surround- 

 ing lint becoming badly stained. Consequently where Heteropterous 

 cotton pests are abundant, there is a reduction in the percentage of 

 seed capable of germinating. This phase of the subject of plant-bug 

 damage has received no especial attention. 



Proof that described injury is due to plant-hugs. — The evidence that 

 plant-bugs cause injury such as described above amounts to positive 

 proof. Sufficient evidence was given by the author in a previous 

 report and, although much more might be added, it is unnecessary to 

 more than summarize the facts there presented: 



1. In a field where the number of conchuelas averaged about 15 

 per acre and the number of other plant-bugs was a negligible quantity, 

 a specimen of the species named (Pentatoma ligata Say) was known to 

 have fed on a single boll for over 36 hours. After several days, 

 during which no bugs were found on this plant, the 15 bolls found on 

 this plant were cut open and examined, with the result that only the 

 one upon which the insect was known to have fed showed the injury 

 described. 



