186 
THE PLUM CUKCULIO. 
the poison was applied much too freely, and as used would undoubt- 
edly have acted as a repellent. In the case of Paris-green sprays in 
water there could be no repellent action attributed, and with arsenate 
of lead, as used in practice, it would seem established that its value 
lies more in killing of the insects than in possible repellent action. 
In the course of these studies numerous feeding tests have been 
made with the curculio, especially with different brands of arsenate 
of lead and other miscellaneous arsenicals. Results of a feeding test 
made in 1906 are shown below (Table XC), where apple, pear, peach, 
plum, and cherry branches bearing foliage and fruit were used. 
Twigs of plants placed in bottles with water were used and all were 
sprayed at some time with arsenate of lead at the rate of 2 pounds 
to 50 gallons of water, using a hand pump and Vermorel nozzle. 
With each fruit the poison test was made in duplicate with a single 
check. After the spray had dried on the foliage the branch was 
placed under a large cylinder with cloth over top, and 20 beetles, 
collected that morning by jarring, were added. 
Table XC. — Tests of the hilling effect of arsenate of lead on the plum curculio on 
specified fruits, Washington, D. C, 1906. 
Apple. 
Pear. 
Peach. 
1 
Plum. Cherry. 
Dates of examination. 
73 
9.6 
'S-a 
-w c 
o o 
73 
96 
■8. 
go 
Oirj 
P. 53 
-w c 
o o 
2 ra 
73 
a> • 
OT O 
oB 
Ph 
73 
2n 
59 O 
"SB 
73 
o ■ 
id 
Ph 
Poisoned 
No. 2. 
Not poi- 
soned. 
Poisoned 
No. 1. 
73 
§^- 
9.6 
pZ 
ti 
b m 
June 25 
6 
4 
4 
2 
16 
4 
10 
2 
2 
2 
16 
4 
.... 
1 
19 
4 
3 
6 
6 
2 
6 
6 
2 
.... 
2 
1 
2 
10 
4 
4 
5 
3 
5 
6 .... 
3 .... 
3 .... 
1 .... 
2 
4 
4 
1 
4 
5 
1 
26 
4 ---- 
27 
5 
4 
"i" 
28 
j 
Total 
19 
1 
16 
4 
3 
17 
13 
7 
17 
3 
19 
17 
3 
13 
7 
26" 
17 
3 
17 
3 
?, 
Beetles alive at close of observations. . 
18 
The results uniformly show a prompt killing effect on the beetles 
by the arsenate of lead on the varieties of fruits used. It is also 
evident that the insects feed freely during midsummer. 
During 1910, in Georgia, numerous feeding tests were made using 
several of the more important brands of arsenate of lead, as well as 
other miscellaneous arsenicals. In Table XCI are given results of 
feeding tests on peach twigs taken from trees in orchards immediately 
after spraying, April 13 and 14, and placed under cylinders. April 
16, 50 beetles were added to each cylinder and records made daily 
of the number of beetles dying. The poisons were used of the strength 
indicated in the foliage test experiments (p. 205). The killing effect 
of all of the poisons was fairly prompt, the various brands of arsenate 
of lead working fairly uniformly. Red arsenic sulphid and arsenic 
tersulphid were quicker in action than the lead arsenates, although, as 
elsewhere noted, these poisons were notably injurious to the foliage of 
