19 



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

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

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

 in round numbers of 6,000 bales. The resident manager of the 

 plantation ascribed a considerable part 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 plantation at between 1,200 and 1,500 bales. The 

 resident manager of the plantation believed this injury to the bolls 

 to have been caused by a bug which occurred in abundance on tlie 

 cotton plants the previous season. Fragments of several pentatomid 

 bugs found among the fallen leaves under the cotton plants Avere 

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

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

 injur}^ Avhich could be traced to the bolhvorm. 



Specimens of the insect belicA^ed to have caused the injury during 

 the previous season were 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 scA^eral Aveeks 

 after these specimens Avere received. The second visit to Tlahualilo 

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

 period that the obserA^ations recorded in this paper Avere made on the 

 /life history and habits of the insect believed by many to have 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 

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

 a common name and that it should be so generally known 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 several times since, 

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



« The yield of seppa, or zoca cotton as it is liiiown in the Laguna, is not 

 here considered, as it receiA^es only surplus water varying in amount from year 

 to year. 



& Doctor Fitch referred to what he supposed to be this species feeding on 

 juniper and grape in New York State, but it seems probable that his insect was 

 P. juniperina Linn. See footnote, page 20. 



