LIME-SULPHUR A STOMACH POISON FOR INSECTS. 



85 



Table III. — Tests of the killing effect on the fall webworm of lime-sulphur in comparison 



with arsenate of lead. 



[Experiment started August 8, 1912, Benton Harbor, Mich., 20 larvae in each lot.] 





Larvae dying in each lot. 



Date of examination. 



Lotl— 



Check 

 (un- 



spray- 

 ed). 



Lot 

 2— 

 Lime- 

 sul- 

 phur, 

 4-50. 



Lot 

 3— 

 Lime- 

 sul- 

 phur, 

 1-50. 



Lot 

 4— 

 Lime- 

 sul- 

 phur, 

 1J-50. 



Lot 

 5— 

 Lime- 

 sul- 

 phur, 

 2-50. 



Lot 

 6— 

 Lime- 

 sul- 

 phur, 

 3-50. 



Lot 

 7— 

 Lime- 

 sul- 

 phur, 

 5-50. 



Lot 

 8— 

 Lime- 

 sul- 

 phur, 

 6-50. 



Lot 



9— 

 Arse- 

 nate 



of 

 lead, 

 1-50. 



Lot 

 10— 

 Arse- 

 nate 

 of 

 lead, 

 1-50. 



Lot 

 11— 



Arse- 

 nate 

 of 

 lead, 

 2-50. 



Lot 



12— 

 Arse- 

 nate 



of 

 lead, 

 5-50. 



Aug. 10 

















2 

 3 

 11 



4 



...... 



11 

 3 

 4 

 1 



2 

 2 

 10 

 2 

 4 



8 

 11 



1 





12 















1 



6 

 6 



7 



15 



14 





1 

 3 

 2 

 8 

 6 



4 



8 

 8 



5 

 13 

 2 



2 

 6 

 8 

 4 



3 

 6 

 11 





16 







18 









20 









22 





















Sept. 2 



2 

 3 

 2 





















10 

























Oct. 19 

















































Total number dead. 



Number days required to 



kill 



7 



20 



14 



3.92 



20 



10 



0.36 



20 



10 



0.17 



20 



12 



1. 01 



20 



10 



0.S1 



20 



10 



0.73 



20 



8 



0.26 



20 



14 



2.38 



20 

 10 



1.98 



20 



6 



0.11 



20 

 6 



Square inches of foliage 



119. 00 



0.10 







It will be noted that lime-sulphur, -J-50, killed the 20 larvae in 14 

 days, the same length of time required by arsenate of lead, J— 50. 

 Also lime-sulphur, 1-50, killed the larvae in the same length of time 

 as arsenate of lead 1-50, the time required being 10 days. However, 

 in both instances the arsenate of lead killed more rapidly in the 

 beginning than the lime-sulphur. Eight days were required by 

 lime-sulphur, 6-50, to kill the 20 larvae as against 6 days required by 

 arsenate of lead, 5-50. The amount of feeding varied somewhat in 

 this experiment, the largest amount on the sprayed lots being 3.92 

 square inches where lime-sulphur, J— 50 was used, and the smallest 

 amount being 0.10 of a square inch in lot 12 which was sprayed with 

 arsenate of lead, 5-50. 



Experiment IV. 



The object of experiment IV was to obtain data on the relation of 

 the killing effect of arsenate of lead alone and combined with lime- 

 sulphur, and to obtain, if possible, data on the effect the addition of 

 one to the other has upon the rapidity of killing. Lime-sulphur 

 alone was used at four different strengths, and also was combined at 

 the same rates with arsenate of lead, 2-50. The lime-sulphur 

 strengths employed were J-50, f-50, 1J-50, and 3-50. Arsenate of 

 lead, alone, was tried out at strengths of ^-50, 1-50, 2-50, 3-50, and 

 5-50, and also at the same strengths was combined with lime-sulphur, 

 1^-50. The results are given in Table IV. 



