52 



BULLETIN 918, U. S. DEPARTMENT OF AGRICULTURE. 



Table XXVIII. — Weekly examination of bolls from poison experiments: Average num- 

 ber of larvx per boll. 



Week ending- 



Aug. 2. 

 Aug. 9. 

 Aug. 16 

 Aug. 23 

 Aug. 30 

 Sept. 6. 

 Sept. 13 

 Sept. 20 

 Sept. 27 

 Oct. 4.. 

 Oct. 11. 

 Oct. 18. 

 Oct. 25. 

 Oct. 31. 



Tlahualilo. 



Zaragosa. 



Poison. Check. 



0.05 



0.13 



.11 



.09 



.26 



.23 



.31 



.38 



.57 



.88 



1.2 



.86 



l.S 



5.10 



1.83 



1.50 



1.45 



5.10 



5.77 



6.90 



6.40 



8.40 



7.60 



8.10 



7.20 



5.50 



S.70 



9.80 



Small experiment. 



Poison. Check. 



1.2 

 1.7 



2.3 

 3.2 

 1.2 

 2.4 

 4.0 

 4.2 

 6.0 

 3.9 



0.66 



.44 



.46 



.32 



1.6 



3.0 



4.5 

 5.0 



5.7 

 4.0 



San Isidera. 



Poison. Check 











.02 



.04 



.02 



.14 



.20 



.25 



.27 



1.50 



3.70 



5.50 



8.00 



7.00 













 .05 

 .03 

 .06 

 .10 

 .14 

 .28 



2.30 



3.0 



5.30 



.10 



Lerdo. 



Poison. Check 



0.62 

 .80 

 3.50 

 4.34 

 4.16 

 2.8 

 4.6 



6.28 



5.70 



0.62 

 .80 

 3.88 

 3.14 

 3.52 

 2.7 

 4.8 



5.84 



Weekly examinations of bolls both from the poisoned and check 

 plats were made. The average number of larva? per boll varied 

 slightly. These variations, however, occurred in other samples of 

 bolls where no poison was used and the poisoning did not check the 

 infestation. The season of experiments was unfavorable for poison- 

 ing experiments. There was about twice the normal rainfall, which 

 washed the poison from the plants, and, moreover, caused the cotton 

 to grow so rank that it was impossible to get a thorough application 

 with the available labor. Under more favorable conditions it is pos- 

 sible that better results might be obtained. 



TRAPS. 



Trap Lights. 



In the laboratory, where the doors and windows were screened and 

 the moths could not escape, they would frequently come to the elec- 

 tric lights, resting on the shade or wall near by, but under outdoor 

 conditions moths would seldom come to lights. Acetylene and elec- 

 tric lights were suspended repeatedly in front of a white background 

 in the laboratory cotton plats, where there were thousands of moths. 

 In the course of 2 or 3 hours not more than 6 to 8 moths would 

 come to the lights, while at the same time an examination with a 

 flashlight would show there were large numbers on the plants only a 

 few feet away. The few that did come to the lights were probably 

 ones that we disturbed in moving about, and it can not be said there 

 was any attraction whatsoever to the lights. 



An electric trap light was also placed within a few feet of the plants, 

 with negative results. Another trap light was run all night for 15 

 consecutive nights in an open shed where there were hundreds of tons 

 of seeds and only 5 moths were taken. During the same 15 nights 



