PINK BOLLWOEM OF COTTON IN MEXICO. 



45 



are pink with crawling larvae. Many of the double seeds are torn 

 apart in the cleaner and gin, though some go through unharmed. 

 It is extremely disappointing to look for larvae in seed which comes 

 from heavily infested cotton. In such seed in the winter or spring 

 one can rarely collect more than 75 to 100 live larvae in the course of 

 an eight-hour day. Ten samples of 2,500 seeds each were taken on 

 different occasions during February and March, 1918 and 1919, 

 from seed houses, examined seed by seed, and only 9 live larvae were 

 found. 



For our rearing work larvae were removed by hand from the bolls 

 and placed in fruit jars with seed to pass the winter. Table XXII 

 shows that the mortality among larvae removed from bolls in No- 

 vember and stored in the laboratory during the winter of 1918 and 

 1919 was 22.6 per cent and that 0.4 per cent were still alive November 

 20, 1919, when the work was discontinued. 



Other larvae were disturbed as little as possible and were left in 

 the double seed where they had prepared to spend the winter. The 

 double seed were picked from the lint by hand and stored in the 

 laboratory under the same conditions as the others. Table XXIII 

 shows that there was 16.2 per cent mortality among larvae in double 

 seed and that 4.4 per cent were still alive on November 20, 1919. 



Table XXII. — Mortality among larvse, removed from bolls and kept in the laboratory in a 

 condition as near to that of stored seed as possible. 



Date collected. 



Number 



entering 



resting 



stage. 



Number 

 emerged. 



Per cent 

 mortality. 



Per cent 

 emerged. 



Number 



alive Nov. 



20, 1919. 



1918. 

 Sept. 30 



83 

 281 

 256 

 269 

 260 

 282 

 309 

 239 

 320 

 299 

 277 

 260 

 244 

 265 

 125 



71 

 191 

 180 

 153 

 183 

 220 

 255 

 201 

 255 

 244 

 211 

 193 

 192 

 242 



99 



13.2 

 31.6 

 28.9 

 43.1 

 29.7 

 22.0 

 17.5 

 15.4 

 19.6 

 17.7 

 23.4 

 25.0 

 20.9 

 8.6 

 20.8 



85.5 

 68.0 

 70.3 

 56.9 

 70.3 

 78.0 

 82.5 

 84.1 

 79.6 

 81.6 

 76.2 

 74.2 

 77.7 

 91.3 

 79.2 



2 



2 



2 



















1 



2 



2 



1 



2 



1 



1 • 







Nov. 13 



Do 



Do... 



Nov. 14 



Do 



Do 



Do 



Do 



Do 



Nov. 16 



Do 



Nov. 17 



Nov. 19 



Total 



3,769 



2,890 







16 

 0.4 per cent. 



22.6 



77.0 











The moths were removed daily and a record kept for each jar. 

 The percentages used are based on the number of moths emerging 

 and the number of dead and live larvae found in the jar at the end 

 of the experiment. As these larvae were carefully removed by 

 hand and stored indoors, the mortality was the minimum that can 

 be expected and is much lower than in seed ginned and handled 

 on a commercial scale. It is difficult to determine the mortality 



