MISCELLANEOUS INSECTICIDE INVESTIGATIONS. 



Experiment III. 



COMPARISON OF THE KILLING EFFECT OF VARIOUS ARSENICALS ON LARVAE OF THE FALL 



WEBWORM. 



Ill this experiment the same arsenicals were used as in Experiment 

 I, all the other materials being omitted. However, since half-grown 

 larvae were used the strength of the materials was doubled. The 

 results are shown in Table III. 



Table III. — Tests of the hilling effect of various arsenicals on the fall webworm. Larvse 



half grown. 



[Experiment started July 24, 1912, Benton Harbor, Mich.; 20 larvse in each lot.] 



Name and dilution. 



Arsenate of lead, di. , 2-55 



Arsenate of lead, tri., 2^i2 



Arsenate of lead, di. and tri., 2-50 



Arsenate of lead, triplumbic, com. (1), 



4-50 



Arsenate of lead, com. (2) , 4-50 



Arsenate of lead, com. (3), 4-50 



Arsenate of calcium, c. p. (powder), 2-50. 

 Arsenate of iron, e. p. (powder), 4-50... 



Arsenate of iron, h. m.. 3 T V50 



Arsenate of zinc, c. p. (powder), 2-46. . . 



Arsenate of zinc, h. m., l T V-50 



Arsenic sulphid , 2-54 



Arsenic tersulphid , 1-50 



Arsenic trioxid, 1-56 



Arsenite of lime, 4 pts.-50 



Arseniteof zinc, c. p. (1), 2-43 



Arsenite of zinc, com. (2), 3-50 



Arsenite of zinc, com. (3), li-50 



Arseniteof zinc, com. (4), 1J-50 



Check (unsprayed) (1) 



Check (unsprayed) (2) 



Dates of examination and number of 

 larvse dying in each lot. 



July. 



26 27 28 29 31 



August. 



2 4 7 12 



Total 

 num- 

 ber 

 dead. 



Num- 

 ber 

 days re- 

 quired 

 to kill. 



20 

 20 

 20 



20 

 20 

 20 

 20 

 12 

 9 

 20 

 20 

 20 

 20 



U9 

 20 



118 

 20 

 20 



119 

 

 



Square 

 inches 

 foliage 

 con- 

 sumed. 



1.22 

 .60 

 .43 



.84 



.94 



.37 



1.15 



( 2 ) 



( 2 ) 

 2.03 

 .87 

 .95 

 .19 

 .06 

 .56 

 .15 

 1.08 

 .94 

 .41 



( 2 ) 



( 2 ) 



1 Remainder escaped. 



2 Not measured. 



The results of these tests agree very well with the results obtained 

 from Experiment I. The experiment was discontinued August 12, 

 when all the larvse were dead except in the case of arsenate of iron, 

 chemically pure, where 8 larva? still remained living, and arsenate 

 of iron, homemade, where 11 remained living. All the larvse on the 

 unsprayed lots were alive at the time the experiment was closed. 



Experiment IV. 



FIELD TESTS OF VARIOUS ARSENICALS AGAINST THE CODLING MOTH IN MICHIGAN, 1912. 



Several arsenicals were tested in comparison with arsenate of lead 

 against the codling moth in Mr. J. T. Beckwith's apple orchard in the 

 vicinity of Benton Harbor. The trees were of the Ben Davis variety 

 and about 35 years of age. The plats consisted of from 4 to 12 trees, 

 and the fruit was counted from 3 trees of each plat. The extent of 

 foliage injury from the various sprays was also noted. The homemade 



