- 11 - 
Lygus oblineatus (L.)j the tarnished plant bug 
The Ontario Department of Agriculture (69_) in 1934 reported that 
derris extract was of little -value for the control of the tarnished 
plant bug on celery. 
Thompson (85) in 1934 recorded tests against the tarnished plant 
bug on celery in Ontario, Derris powder mixed with fresh hydrated lime 
was used at the rate of 1 pound of derris to 20 pounds of lime as a dust. 
The material was applied with a hand duster on a calm day. Penetration 
was poor, and examinations carried on over a period of 2 weeks failed to 
show any difference in the extent of damage on the treated rows, as con- 
pared with those in the check. Derris was also applied as a spray at 
the rate of 1 pound of derris to 20 imperial gallons of water to which 
a quarter of a pound of laundry soap had been added. The active principle 
of the derris was extracted by treating the pound of powder with 1 pint 
of methyl alcohol. Derris did not prove of any value against any stage 
of the tarnished plant bug, either as a dust or as a spray. 
Cory (37) in 1935 reported that rarcovitch of Tennessee obtained 
verv good cent. ol in case tests with a dust consisting of 1 part of 
v O O OX 
derris and 7 parts of talc. 
The Division of Cotton Insect Investigations of this Bureau, in 
a memorandum to R. C. Roark, dated December 2, 1936, reported the following 
results of tests against the tarnished plant bug at Tallulah, La,, and 
Port Lavaca, Tex., in 1936: 
Treatment 
Derris 40 percent, sulfur 60 percent 
( rotenone 1,6 percent) - - - 
Derris 20 percent, sulfur 80 percent 
(rotenone 0.8 percent) - - - 
Derris 10 percent, sulfur 90 percent 
(rotenone 0.4 percent) - - - 
Derris (rotenone 4 percent)- --------- 
Check- -- _______________ 
Cube (rotenone 4 percent)- ---------- 
Sulfur -------------------- 
Tephrosia virginiana (rotenone 1,7 percent)- - 
Mor tality 
Nymphs Adults 
Percent Percent 
43.1 
47.1 
36,7 
68.2 
28.9 
64.5 
O <^ # i? 
43.3 
46, 
,7 
76, 
,8 
59 
4 
78, 
,7 
66, 
,6 
67, 
,5 
45, 
6 
54, 
,6 
