66 PLANT-BUGS INJURIOUS TO COTTON BOLLS. 



estimates which have already been referred to placed the number of 

 conchuelas on the entire tabla at about 60,000. At the rate of one boll 

 destroyed for each three-fourths of a day, it may be calculated that 

 on July 15 the bugs had been in the field an average of 16 days each. 



Estimates made after December 1, the details of which will be 

 found elsewhere, placed the destruction by bugs in Ceceda A, tahla 14, 

 at approximately 28 -bales, not taking into consideration the bolls 

 which were shed from the plants as a result of injury by these insects. 

 The estimate of 60,000 conchuelas in the entire tabla was based on 

 data obtained on July 15, after which there was a slight increase. 

 Reference to Table XXVI will show that an estimate of 65,000 bugs 

 is not too high for the maximum number of live conchuelas in this 

 tabla at any time in July. For each 2,300 bugs, therefore, about one 

 bale of cotton was destroyed. Considering the loss of one bale of 

 cotton as equivalent to the moderate sum of $45, on the average each 

 bug in the tabla destroyed cotton to the value of about 2 cents. This 

 estimate can not be considered as representing even approximately 

 the amount of damage by a single conchuela except under conditions 

 similar to those described. General deductions of wider application 

 may, however, be drawn from the data given. 



From a comparison of the average maximum and minimum num- 

 ber of punctures per damaged boll in Ceceda A, tabla 14 (Table XXV), 

 it is evident that the bolls were much fed upon by the bugs after they 

 had received sufficient injury to result in complete destruction. 

 Fortunately such feeding prevents a maximum amount of damage. 

 The average of the ruined bolls of the various sizes with the minimum 

 number of punctures is 15.4, or about one-third of the average num- 

 ber of punctures for all bolls. Even this number is greater than 

 usually necessary for the destruction of bolls, as the data given show. 

 On the other hand, many punctures are made in bolls which have 

 reached such a stage of maturity that there results either no appre- 

 ciable damage or only a staining of the lint to a greater or less degree. 



The habit of the conchuelas of congregatmg on individual plants 

 and even on individual bolls has a tendency to result in an excess of 

 feeding punctures above the number necessary to cause destruction. 

 Data have been given in Table III showing that at Dallas, Tex., in a 

 field where plant-bugs were less abundant than in Ceceda A, tabla 14, 

 at Tlahualilo, the average number of punctures per destroyed boU 

 was 28. For convenience we may suppose that in a field infested by 

 the conchuela, where the damaged bolls average 28 punctures per 

 boll, it is desired to estimate the amount of damage the individual 

 bugs may accomplish. At the average rate of 56 punctures per day, 

 which is the estimated number, the bugs would have averaged 2 



