INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 5 
Rotenone- and pyrethrum-containing sprays and dusts, and helle- 
bore, are tolerated by most plants and rarely cause injury. 
Either sodium fluosilicate or barium fluosilicate, even when diluted 
with five times its weight of clay as for the control of blister beetles, 
will cause injury under some conditions, and many plants will not 
tolerate them. Cryolite applied at the recommended dosages is nor- 
mally tolerated by most plants, but corn is particularly sensitive to 
this material as well as to other fluorine compounds. Sodium fluoride 
should not be used as a plant insecticide, as it may destroy the plant. 
Soap sprays, especially when used at “high concentrations, will in- 
jure the leaves of such tender plants as young cabbage or cauliflower 
in seed beds, or garden peas and young beans, as well as many tender 
ernamental plants. 
The dosages of insecticides recommended in this publication are 
based, in general, upon the minimum quantities that will control the 
insects and that are within the range of dosages the plants will tolerate. 
ARSENIC TRIOXIDE 
Arsenic trioxide (As,O5 ), or arsenious oxide, is a crystalline ma- 
terial usually sold as “white arsenic.” It is largely obtained as a by- 
product in the flue dust from smelters. In normal times our supply 
comes from both domestic and foreign sources. In somewhat impure 
forms it is marketed as off-white arsenic under names indicating its 
color, such as gray arsenic. Arsenic trioxide is the starting material 
in the manufacture of the arsenical plant insecticides. Because of its 
adverse effect upon plant tissue it is not used as a plant insecticide, but 
is used in the compounding of poisoned baits for the control of orass- 
hoppers and cutworms and certain other insects. (See Poisoned Baits, 
p. 28.) 
Caution.—Arsenic trioxide is a violent poison and must be 
stored in a safe place and in plainly labeled containers. The 
powder should not be inhaled, and it should not be permitted to 
come in contact with the skin, especially open wounds. 
BARBASCO 
See Rotenone-containing Roots (pp. 30-32). 
BARIUM CARBONATE 
Barium carbonate (BaCO;), a domestic, natural, chalklike sub- 
stance, is ground to a powder and used as an insecticide in some cases, 
but it is better known as a rat poison. Rather heavy dosages are 
required to protect plants from attack by chewing insects, such as the 
Mexican bean beetle (14 pound to the gallon of water). 
Caution.—Barium carbonate is poisonous to man-and animals 
when taken into the intestinal tract, and care should be exercised 
in handling it. 
BARIUM FLUOSILICATE 
Barium fluosilicate (BaSiF,), a domestic product, has been used 
against some insects. While somewhat useful in the control of the 
