THE CONCHUELA. 



51 



Bugs were picked from the plants on this tabla between the exam- 

 inations of July 11 and 15 and again between the examinations of 

 July 27 and 29, the first pickings averaging about 7 per row and the 

 second averaging between 5 and 10. The removal of these may be 

 taken into consideration, although affecting the general results but 

 little. The data obtained by these examinations show that con- 

 chuelas, or in a broader sense the Pentatomids, reached their maxi- 

 mum numbers in this field about July 20, and during the following 

 week there was a decrease of nearly 50 per cent. Considering the 

 picking just previous to the last examination, a continuance of the 

 natural decrease in numbers is evident. 



Following the same general plan, four additional examinations 

 were made on July 15 for the purpose of showing the numerical status 

 of the bugs on that date throughout the tabla. The length of the 

 tabla being about one and one-quarter miles, five examinations were 

 made, one at each end and three between, at places estimated to 

 divide the tabla into fourths. Table XXII shows the data obtained 

 by these examinations. 



Table XXII. — Numerical status of Pentatomid bugs infield of 120 acres, July 15, 1905. 



Examination 

 No. 



Number 

 of plants 

 in row. 



Number 

 of plants 



infested 

 bv adults 



per 100. 



Number of 

 adults P. 

 ligata per 



100 plants. 



Number of 

 nymphs P. 



ligata on 

 lOOplants.a 



Number of 



adults P. 



sayi per 



100 plants. 



Number of 



adults Ttiy- 



anta sp. 



per 100 



plants. 



Total adult 

 Pentato- 

 mids per 



100 plants. 



1 



99 

 82 

 103 

 127 

 56 



30 

 26 

 17 

 5.5 

 12.5 



52 

 57 

 33 

 7.8 

 21.4 



13 34 

 12 15 

 92 14 





 



3 

 8 

 

 

 



2 



2 



1 

 1 

 1 



57 

 67 

 34 

 8.8 

 22.4 



2 



3 



4 



5 



Total 



Average.. 



467 

 93.4 



91 

 18.2 



171 

 34.2 



16 

 3.4 



11 



2.2 



7 

 1.4 



189 

 37.8 



a Small figures indicate the instars. 



As there were nearly 1,660 rows in the above tabla, it may be esti- 

 mated from the data given that there were on July 15 approximately 

 60,000 conchuelas in the entire area of 120 acres. 



Another series of observations made in planta cotton in Zaragoza B, 

 tablas 1-9, also shows a diminution of the pest during the last 10 days 

 of July. A single row was examined on each tabla about 200 yards 

 from the east end, the rows running north and south. 



