INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 



Rotenone- and pyrethrum-containiiig 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 beetle.-, 

 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 

 ornamental 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 2 3 ), 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 such as lead 

 arsenate and calcium arsenate. 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 grasshoppers 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 (BaC0 3 ), 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 (i/ 2 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 6 ), a domestic product, has been used 

 against some insects. While somewhat useful in the control of the 



