14 
BULLETIN 278, U. S. DEPAETMENT OF AGEICULTUEE. 
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. I closed. 
IE 
3 a> 
-2 = 
2 
Eriocampoides cerasi. 
Hyphantria cunea . 
Halisidota caryse. 
Datanaministra. 
20 
Check (unsprayed) 
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, 
l*-50. 
....:do 
Check (unsprayed) 
Arsenate of lead, commer- 
cial, 2-50. 
do 
Lead chromate, commer- 
cial, 2-50. 
do 
Lead chromate, homemade, 
f-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, 
H-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. 8 
..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.... 
*ug. 1 
.do.... 
.do.... 
..do.... 
Aug. 14 
Aug. 10 
...do.... 
Aug. 14 
Aug. 13 
Aug. 10 
9.64 
4.36 
0.25 
3.48 
3.39 
41.00 
37.00 
.08 
.72 
1.04 
3.50 
2.20 
.30 
.50 
3.25 
3.50 
1.50 
1.60 
Remainder pupated. 
2 Remainder escaped. 
Against the fall webworra {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 in the 
case of arsenate of lead used at the rate of 2 pounds to 50 gallons 
of water. The strength of lead chromate in this case is four tunes 
greater than was used against the pear slug. Lead chroinate, home- 
made, was used at the rate of 1 J 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 larvae were dead in each lot of the checks at the end of the 
experiment, which was closed July 31. 
The experiment against Halisidota caryae ran for 18 days,at the 
end of which time the lead chroinate, commercial and homemade, 
