THE CONCHUELA. 



57 



bolls per day destroyed instead of If bolls per day estimated in 

 Ceceda A, tahla 14. As the percentage of damaged bolls increased, 

 the daily damage per bug would diminish. If the increase in the 

 number of new bolls was sufficient to prevent an actual increase in 

 percentage of damaged bolls, the average daily injury for each bug 

 would remain fairly constant at 2 bolls per day, and the ultimate 

 damage, if in the same ratio as that which obtained at Tlahualilo in 

 the field, to which the data refer, would be 60 per cent more than 

 estimated for that field, or an equivalent of 3 J cents for each bug. 



From estimates made at Tlahualilo on the numerical status of 

 the insects in July and on the percentages of ruined bolls in December, 

 the relationship of the number of bugs present during the period of 

 maximum abundance and the damage accomplished during the 

 season may be presented in tabular form as follows : 



Table XXVI. — Relation ofnumher ofconchuelas to amount of damage. 



Field. 



Number of 

 adult con- 

 chuelas per 

 100 plants, 

 July 23-25, 

 1905. 



Number of 

 adult con- 

 ch uelas per 

 row, July 

 23-25, 1905. 



Average 



number of 



bales good 



cotton per 



acre. 



Average 



number of 



bales 



ruined 



cotton per 



acre. 



Percentage 

 of ruined 

 cotton. 



Zaragoza B, ^a&Za 1. east quarter 



9.6 

 1.7 

 46 



30 

 3.5 



46 



0.412 

 .644 

 .216 



0.246 

 .11 

 .221 



37 



Zaragoza B, tabla 3, west quarter 



14 





50 







The percentage of injury in Ceceda A, tahla 14, is so far above the 

 ordinary that it may be properly considered as representing an 

 extreme case, while the individual conchuelas, for reasons given, 

 accomplished a minimum amount of damage, equivalent to about 

 2 cents. The maximum amount of damage for the individual con- 

 chuelas would be difficult to determine without a long continued 

 series of observations, but it is probably equivalent to not more 

 than 2 or 3 cents above the minimum amount. These estimates, 

 while necessarily only approximating actual conditions, will serve to 

 give a general idea of the damage an individual conchuela or other 

 plant-bug is capable of causing. A knowledge of this point is an 

 essential step in the determination of the practicability of various 

 remedial measures. 



REDUCTION IN YIELD OF INFESTED COTTON FIELDS. 



As has been stated, the estimated loss to the cotton crop of 1903 

 at Tlahualilo was between 1,200 and 1,500 bales. Accordingly this 

 loss for the entire acreage in planted cotton — amounting to about 



