DESTRUCTION OF COTTON FORMS. 



65 



of stages the proportion shown by Table VI to have reached the 

 adult stage in Louisiana and Texas in 1906 (i. e., about 17 per cent), 

 it would appear that this work of collection prevented the emergence 

 of from 34,000 to 42,500 adult weevils upon an area of 8 acres. 

 When it is considered that in spite of this large destruction of weevils 

 the resulting increase in yield averaged hardly 50 pounds of cotton 

 per acre, the reader will be able to realize more clearly than he could 

 without such a comparison the tremendous importance of the factors 

 of natural control which do, under exceptionally favorable conditions, 

 make it possible to produce a very profitable crop, because of their 

 direct effect in reducing the number of weevils which reach maturity. 

 It will be understood, also, that the total mortality resulting from all 

 factors 'must become very large indeed in order to reduce the damage 

 done by the small percentage which do survive, so that the develop- 

 ment of the crop may far outstrip the insect attack. 



COLLECTIONS OF FALLEN AND OF DRIED HANGING FORMS IN 1906. 



In Tables XV and XVI are presented some of the results from 

 the work of 1906. In these tables, however, it is possible to include 

 a statement of the number of weevil stages found in each examina- 

 tion. , In the collection of this material there was no particular selec- 

 tion of squares or bolls, but all forms were taken as they occurred. 

 Special collections were made, however, for hanging and for fallen 

 forms, so that the proportion of hanging and of fallen forms could 

 not be considered as an indication of the proportion which actually 

 existed upon the area from which collections were made. This 

 explanation applies both to Table XV and to Table XVI. 



Table Xy. — Proportion of fruit destroyed by insect injury or by natural causes, 



Louisiana, 1906. 



Class of fruit examined, and 

 locality. 



Fallen bolls: 

 Mansfield 

 Mansfield 

 Mansfield 



Many 



Many 



■ Orangevilh 



Date. 



Aug. 24 

 Aug. 24 

 Sept. 29 

 Aug. 23 

 Aug. 2.3 

 Aug. 23 



O range vi lie i Sept. 30 



Totals, fallen bolls. 



Fallen squares: 



.Johnsons Bayou. 

 Mansfield ....... 



Mansfield 



Mansfield 



Many 



Many 



Orangoville 



Orange ville 



Totals, fallen squares. 



A.ug.22-27 



Aug. 24 

 Aug. 24 

 Sept. 29 

 A.ug. 23 

 Aug. 23 

 Aug. 23 

 Aug. 23 



Total ex- 

 amined. 



11575— Bul. 74—07- 



450 



400 

 372 

 555 

 534 

 145 

 150 



300 

 400 

 525 

 37 

 875 

 l 133 

 400 

 500 



4.170 



Weevil stages not 

 found. 



Number 

 of forms. 



392 

 300 

 332 

 402 

 390 

 109 

 119 



2, 050 



78 

 193 

 268 



20 

 336 

 •107 

 I 12 

 332 



1,776 



Per cent 

 of total 



exam- 

 ined. 



87.1 

 75.0 

 89.2 

 72.4 

 74.2 

 75.2 

 79.3 



78.7 



20. 

 is. 25 

 51.0 

 54.1 

 38. 1 

 :;;, '.i 

 35. ."- 

 66. 4 



42. 6 



Infested by weevil. 



Number. 



58 

 L00 



in 

 153 

 L38 

 36 

 31 



556 



222 

 207 

 257 

 17 

 539 

 726 

 258 

 L68 





Percent 

 of total. 



12.9 

 25. 

 10.8 

 27. 6 

 25. 8 

 24.8 

 20.7 



21.3 



74.0 

 61 

 49. o 

 45. 

 61.6 

 04.1 

 64.5 

 33.6 



/.) 



57.4 



Total 

 weevil 



stages 

 found. 



58 

 106 



47 

 153 

 168 



36 



31 



599 



207 

 257 



17 



259 



170 



2, 108 



