31 



a very similar plant standing 3 feet away in the same row; 14 of 

 these Avere perfect in every way, 1 boll was injured by a boll worm, 

 and the remaining injured boll had the appearance of having been 

 fed upon when quite small by P. ligata or some other heteropterous 

 insect. One lock of this boll was decidedly stunted, giving it a de- 

 formed appearance. The inside of the carpel of the stunted portion 

 showed the characteristic mark of injury already described, as did 

 several seeds with the surrounding lint. 



On September 8 an examination was made of the bolls of a plant 

 upon which three specimens of P. ligata were taken on September 6. 

 As before, the surrounding plants were free from the insects and their 

 bolls only in few instances showed injury of the nature described as 

 occasioned by this species. Of the 64 bolls over 1 inch in diameter 

 which were on the plant, 20 were selected at random and carefully 

 examined, and but 2 of them were found to be uninjured. 



As the above observations might lead to an exaggerated idea of 

 the injury believed to be caused by the insect here considered, it 

 should be explained that in the field where the above instances oc- 

 curred the conchuelas at the time were more abundant than elsewhere 

 on the plantation, and CA^en here (with the exception of a limited 

 area) on not more than 5 or 6 stalks to an acre could the insects be 

 found. The observations indicate, however, that when they are very 

 numerous the conchuelas are capable of causing considerable damage 

 to the cotton crop. 



The exceptional area referred to above consisted of about 300 

 square feet in the cotton field, which was slightly lower than the 

 general level. The plants were consequently growing more via'or- 

 ously, and more adult conchuelas Avere found at Avork here than else- 

 Avhere. An exan:iination of all the bolls over 1 inch in diameter on 

 10 representatiA^e stalks shoAved that 33. per cent of them were injured, 

 and of the open bolls on these plants 19 per cent had at least one lock 

 damaged by shriveling, apparently caused by the attack of a heterop- 

 terous insect. 



As a check to this examination, 30 bolls, from one-third to three- 

 fourths groAvn, Avere examined on a portion of the plantation Avhich 

 Avas remarkably free from insects, and Avhere no heteropterous insects 

 of ^\\j kind could be found. Each lock in each boll Avas carefully 

 examined as before, Avith the result that only 2 bolls Avere found to 

 shoAv the slightest internal discoloration, and this did not extend to 

 the seed, nor was it accompanied by the spot on the inside of the 

 carpel, Avhich the evidence obtained showed to result from the punc- 

 ture of P. ligaM. 



Cage experiments were conducted for the purpose of learning hoAv 

 long after a boll is fed upon the injury becomes apparent and 

 also hoAv long feeding must be continued to Avork an injury. Neither 



