PINK BOLLWOEM OF COTTON IN MEXICO. 



37 



that when plants are allowed to float free and move with the current 

 the bolls will remain on the plants longer. When floating in this 

 manner part of the plants are always out of water and, as they revolve 

 more or less, the same bolls will not be submerged all the time and 

 larvae will survive more than 3 days. To determine how long larvae 

 would live in green bolls, sample bolls were placed in a trough 

 and examined daily. The bolls floated and larvse lived for 10 days. 

 On the eleventh day all of the bolls sank to the bottom and were very 

 rotten, and no live larvae were found in them. The results of these 

 experiments are summarized in Table XVIII. 



Table XVIII. — Effect of water on pink bollworm larvae. 



Condition of exposure. 



Number treated. 



Time of 

 exposure. 



Per cent 

 killed. 



Remarks. 







Hours. 











20 



60 









44 



70 







20 larva? and 3 pupae. . 



120 



100 



Larvae lived several davs. 







144 

 48 



100 



70 



















emerged. 





20 larvae 



72 



90 



Heavy cocoons. 





do 



96 



120 



96 



100 

 100 



100 



Do. 







Do. 



Double seed in tube of water... 



10 double seed (.5 lar- 







10 double seed (3 lar- 



124 



66 



2 larvae alive . 



Seed and cocoons in pill boxes 





24 









do 



48 









(3 seeds and 2 cocoons in each 

 box. Counted together). 



....do 



72 



40 





do 



96 











120 



50 



2 pupated afterwards. 







Days. 









do 



6.5 



8 

 11 

 15 

 17 



7 



40 

 60 

 100 

 100 

 100 

 80 







„..,do 







do 







do 











Bolls floating on water in 



20 bolls (29 larvae) 



Bolls covered with algae 



trough. (Bolls picked in 









and rotten. 



December, 1918, andstoredin 



20 bolls (12 larvae) 



11 



100 



Do. 



laboratory. Contained many 



20 bolls (56 larvse) 



14 



100 



Do. 



dead larvse not included in 



20 bolls (17 larvae) 



17 



100 



Do. 



count.) 



120 bolls (273 larvse)... 



18 



100 



Do. 



Bolls submerged in water in 



20 bo Us (30 larvse) 



7 



77 



2 pupated; bolls covered 



trough (same kind of bolls as 









with algse and rotten. 



above). 



20 bolls (113 larvae).... 



11 



100 



1 larva lived several days; 

 bolls rotten. 





20 bolls (46 larvae) 



14 



100 



Bolls rotten. 





20 bolls (14 larvse) 



17 



100 



Do. 





120 bolls (169 larvae)... 



18 

 Hours. 



100 



Do. 



Green bolls submerged in slat- 



10 bolls (37 larvse) 



48 



95 



Bolls fermenting and very 



ted box in river. 









sticky. 





10 bolls 



72 

 96 

 48 



100 

 100 

 55 







10 bolls 





Plant with green bolls attached 



10 bolls (40 larvae) 



Bolls fermenting. 



floating on surface of river, 



9 bolls (19 larvae) 



72 



98.4 



Interior of bolls rotting. 



Sept. 13, 1919. 



7 bolls (11 larvae) 



96 

 Days. 



46 



All of live larvae found in 

 two bolls which were not 

 submerged. 



143 green cotton bolls placed in 



20 bolls (122 larvae).... 



3 



7.3 





container of water. Water 



20 bolls (125 larvae).... 



4 



3.1 



All dead in two badly de- 



changed daily. 









cayed bolls. 





20 bolls (133 larvae) 



5 



6.3 



Decaying. 





20 bolls (107 larvae).... 



6 



60.7 



Some in bad state o f decay. 





15 bolls (84 larvse) 



7 



31.5 



Do. 





16 bolls (73 larvse) 



8 



38.8 



Some bolls rather small 

 and badly decayed. 





10 bolls (61 larvae) 



9 



44.2 



Bolls decaying rapidly. 





10 bolls (51 larvae) 



10 



60.7 



Some still floating; badly 

 decayed. 





6 bolls (43 larvse) 



11 



100.0 



Badly decayed. 





6 bolls (29 larvae) 



12 



100.0 



Very rotten. 



