NATURE OF IK JURY. 15 



correspondent that the discoloration appears as soon as the boll 

 opens. 



Following the foregoing accounts the next reference to the nature 

 of plant-bug damage, so far as known to the writer, is a brief descrip- 

 tion of damage to cotton in Egypt by a Lygseid, Oxycarenus Jiyalini- 

 pennis Costa, published in 1890." This description, which is cred- 

 ited to Dr. E. Sickenberger, states that these insects ''suck the sap 

 from the base of the young pods and from the blossoms and thus 

 prevent their development ; they attack also the seeds when they are 

 tender, which results in a diminution of the germinative strength and 

 consequently a diminution in the product of the plant." A staining of 

 the lint is also mentioned but the exact method by which this injury 

 is brought about is unexplained. 



The cotton leaf-bug (Calocoris rapidus Say) and the bordered plant- 

 bug {Largus succinctus L.) are reported by Mr. F. W. Mally^ to 

 damage cotton bolls, leaving a small, round, black dot at the point 

 of the puncture. He says: ''The injury nearly always has the effect 

 of causing the boll to 'flare' and drop, or if not, then the tuft of 

 cotton in that section of the boll becomes stained." The first 

 accounts of damage to cotton bolls, with Heteropterous insects deter- 

 mined as the cause by definite experimental work, were published in 

 1905, Prof. E. D. Sanderson describing the injury caused by Calocoris 

 rapidus, and the present writer the injury by the conchuela, Pentatoma 

 ligata Say. Concerning the former Professor Sanderson '^ says: "It 

 punctured the squares and young bolls, either causing them to drop 

 or making the bolls shrivel or decay where punctured. The punctures 

 in the boll are indicated by small round black spots resembling dis- 

 eased places, which gradually become larger and sunken." The 

 fullest consideration heretofore published of the nature of the injury 

 caused by the cotton stainers is found in the recent paper by Mr. 

 H. A. Ballou, previously referred to. This author reports no per- 

 sonal observations concerning the staining of cotton lint by the 

 excrement of the bugs but mentions the probability of injury through 

 the feeding of the insects on immature bolls and, later, on the seed at 

 time of the opening of the bolls. 



EXTERNAL EVIDENCE OP PLANT-BUG INJURY. 



As the leaf-bug (Calocoris rapidus) is sometimes present in con- 

 siderable numbers in cotton fields where no external evidence of 

 injury such as described by Professor Sanderson can be found, it 

 seems likely that the sunken spots on the outside of the boll, resem- 

 bling some diseased condition, are not a necessary accompaniment of 



a Insect Life, Vol. Ill, p. 68, 1890. 



6 Bui. 29, o. s., Div. Ent., U. S. Dept. Agr., p. 31, 1893. 



c Farmers' Bulletin 223, p. 20, 1905, 



