14 



BULLETIN 278, U. S. DEPARTMENT OF AGRICULTURE. 



Table VII. — Tests of the hilling effect on four species of insects of commercial and home- 

 made lead chromate in comparison with arsenate of lead. 



[Benton Harbor, Mich., 1913.] 



Name of insect. 



Name of material and 

 dilution. 



Date ex- Date ex- 

 periment periment 

 started. closed. 



= °S 

 "A 



A 3 



s° . 



S ^ 03 



Cos d 



-^: - 

 3 c — 

 -.•— w 



Eriocampoides cerasi. . 



Hyphantria cunea. 



Halisidota caryae. 



Datana ministra . 



Check (unspraved) 



do 



Arsenate of lead, commer- 

 cial, 2-50. 



Lead chromate, commer- 

 cial, 2-50. 



Lead chromate, homemade, 

 |-50. 



Check (unsprayed) 



do 



Arsenate of lead, commer- 

 cial, 2-50." 



do 



Lead chromate, commer- 

 cial, 8-50. 



do 



Lead chromate, homemade, 

 13-50. 



...:do 



Check (unsprayed) 



do 



Arsenate of lead, commer- 

 cial, 2-50. 

 do 



Lead chromate, commer- 

 cial, 2-50. 

 ....do 



Lead chromate, homemade, 



|-50. 

 ....do 



Check (unsprayed) 



Arsenate of lead, commer- 

 cial, 2-50. 



Lead chromate, commer- 

 cial, 8-50. 



Lead chromate, homemade, 

 f-50. 



Lead chromate, homemade, 

 1J-50. 



Lead chromate, homemade, 

 3-50. 



July 2 



..do 



..do.... 



..do.... 



...do.... 



July 14 



..do 



...do.... 



..do. 

 ..do. 



..do... 

 ..do... 



..do... 

 ..do... 

 ..do... 



.do.. 



..do. 

 ..do. 



.do. 

 .do. 



.do. 



Aug. 

 ..do. 



..do. 



..do. 



..do. 



..do. 



July 7 

 ...do.... 

 July 5 



July 7 



...do.... 



July 31 

 ...do 



July 18 



...do.... 

 July 21 



...do.... 

 July 23 



July 21 

 Aug. 1 

 ..do.... 

 July 18 



..do.... 

 Aug. 1 



..do.... 

 ..do 



.do. 



Aug. 14 

 Aug. 10 



...do.... 



Aug. 14 



Aug. 13 



Aug. 10 



9.64 

 4.36 

 0.25 



3.39 



41.00 

 37.00 



.72 

 1.04 



3.50 



2.20 



.30 



.50 

 3.25 



3.50 

 1.50 



1.60 



1 Remainder pupated. 



2 Remainder escaped. 



Against the fall webworm {Hyphantria cunea) lead chromate, 

 used at the rate of 8 pounds to 50 gallons of water, was effective, 

 although 3 more days were required to kill in this case than hi the 

 case of arsenate of lead used at the rate of 2 pounds to 50 gaUons 

 of water. The strength of lead chromate in this case is four tunes 

 greater than was used against the pear slug. Lead chromate, home- 

 made, was used at the rate of 1^- pounds to 50 gallons of water, twice 

 the strength that was used against the pear slug. All the larvae were 

 killed in 7 to 9 days, which was considerably slower than with ar- 

 senate of lead, and considerably more foliage was consumed. Four 

 of the larvse were dead in each lot of the checks at the end of the 

 experiment, which was closed July 3 1 . 



The experiment against Halisidota caryae ran for 18 days,at the 

 end of which time the lead chromate, commercial and homemade, 



