INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 35 



SODIUM FL COSinC ATE 



Sodium fluosilicate (Na 2 SiF 6 ), or sodium silicofluoride, resembles 



sodium fluoride and is sometimes used undiluted a> a substitute for it 

 against roaches. Sodium fluosilicate will injure plants unless used in 

 very dilute form. It is used chiefly as a poison in cutworm, mole 

 cricket, or grasshopper bait. 



Caution. — Sodium fluosilicate is a strong poison and should be 

 kept away from food. 



SULFUR 



Sulfur (S). a native element, is an important fungicide and insecti- 

 cide, as well as a useful adjunct or carrier in many dust mixtures. It 

 comes in several forms for insecticidal use: — as a finely ground 

 powder; as a powder plus a wetting agent, called wettable sulfur; 

 and as flotation paste (see also Liquid Lime-Sulfur and Dry Lime- 

 Sulfur). Much progress has been made in grinding the product, so 

 now it is almost universally available in such fineness that almost all 

 of it will pass through a 325-mesh screen. The most finely divided 

 material available at low cost is the flotation sulfur paste, which is 

 almost colloidal and sticks well to foliage. Sulfur is used for the con- 

 trol of the potato leafhopper (on bean, aster, and dahlia), the cotton 

 flea hopper, the tomato psyllid, red spiders, the phlox plant bug. the 

 tarnished plant bug. and the broad mite. As a diluent for dusts it 

 is often used with lead arsenate, pyrethrum powder, ground rotenone- 

 containing roots, or other materials. (See Oil Dusts. ) A fungicide- 

 insecticide dust to control black spot and rose slugs on roses comprises 

 lead arsenate 1 pound, tobacco dust 1 pound, and sulfur 8 pounds. 

 Flowers of sulfur prepared by sublimation, being too coarse, are not 

 used for dusting plants but may be used by burning to fumigate 

 mushroom houses and greenhouses between crops. 



When sulfur is used on fruit trees it should not be followed by oil 

 sprays before all sulfur residues have disappeared. Oil and sulfur 

 may cause severe foliage injury. 



Caution. — In using sulfur, especially when applying or han- 

 dling it as a dust, care should be taken to prevent getting it into 

 the eyes. If the eyes are affected, do not rub them. It is well to 

 wear goggles and a respirator. 



TAR DISTILLATE 



Coal-tar distillates, commonly called tar oils, have been used as 

 dormant sprays for the control of aphids, the bud moth, and the 

 oystershell scale on apple. These preparations are emulsified so they 

 can be mixed with water. They are also sometimes sold in combi- 

 nation with dormant mineral oil. 



Since they must be combined with mineral oil for the control of the 

 San Jose scale, are caustic to the skin of spray men, and are likely 

 to cause injury to the tree-, tar-oil -prays have been displaced t<> some 

 extent by oil solutions of the dinitro organic compounds (see page 12). 



