19 



The decrease in yield per acre of planta (planted) cotton « on this 

 plantation for the season of 1902-3 as compared with the average 

 yield per acre amounted approximately to one-third hale, or a total 

 in round numbers of 0,000 bales. The resident manager of the 

 plantation ascribed a considerable jDart of this difference to lack of 

 water for irrigation at the most advantageous times on certain parts 

 of the estate. In the cotton fields an examination of various portions 

 indicated that fully 10 or 15 per cent of all the bolls had been ren- 

 dered valuless by some agency. A conservative estimate would place 

 the loss on this jDlantation at between 1,200 and 1,500 bales. The 

 resident manager of the })lantation believed this injury to the bolls 

 to have been caused by a I)ug which occurred in abundance on the 

 cotton plants the previous season. Fragments of severa*l pentatomid 

 bugs found among the fallen leaves under the cotton plants were 

 identified by Mr. O. Heidemann as Pentatoma ligata Say. The 

 injured bolls shoAved no boll weevil attack and less than 1 per cent of 

 injury which could be traced to the boll worm. 



Specimens of the insect believed to have caused the injur}' during 

 the previous season Hvere sent to the Avriter in July, and an accom- 

 panying letter from the resident manager stated that the bugs had 

 appeared in the cotton fields for the first time in the season. It was 

 impossible, howcA'er, to again visit the locality until several weeks 

 after these specimens were received. The second A^isit to Tlahualilo 

 was from August 30 to September 8, 1904, and it Avas during this 

 period that the observations recoi'ded in this paper Avere made on the 

 life history and habits of the insect belicA^ed by many to haA'C occa- 

 sioned damage to the cotton crop of a single plantation amounting to 

 many thousands of dollars. 



HISTORY. 



The species is knoAvn to the natives of Mexico, more especially in the 

 northern part of the country, by the name of " conchuela," a Spanish 

 Avord, meaning '' little shell." That this species should have received 

 a common name and that it should be so generally knoAvn among the 

 cotton groAvers and laboring classes in the leading cotton-producing 

 district in Mexico, indicates in itself that it has long been a common 

 pest in the cotton fields. The species Avas first described in 1831, 

 but, Avhile mentioned in entomological literature seA^eral times since, 

 the Avriter is unable to find mention of it as a pest,^ except for a fcAv 



a The yield of seppa, or zoca cotton as it is known in the Laguna, is not 

 hero consirlerecl. as it receives only surplus water varyiui"; iu amount from year 

 to year. 



'' Doctor Fitch referred to what he supposed to he this species feeding on 

 .iunii)er and grape in New Yorlc State, hut it seems prohahle that his insect was 

 P. juniperina Linn. See footnote, page 20. 



