INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 11 



Chloropicrin may be purchased in 1-pound glass bottles or in cylin- 

 ders of from 1 to 100 pounds capacity. 



CRYOLITE 



Cryolite, or sodium fluoaluminate (Xa :; AlF G ), is a white crystalline 

 chemical which is used as a substitute for arsenicals. Both natural 

 cryolite imported from Greenland and synthetic materials of similar 

 composition are available, and for most uses there is little difference 

 between them. It will not damage beans when used for Mexican bean 

 beetle control, or flowering plants when used to control blister beetles, 

 Fuller's rose beetle, and the black vine weevil. It is frequently used 

 on apple trees for the control of the apple flea weevil and the codling 

 moth, but in the East and Middle West it sometimes causes injury to 

 fruit and foliage. It cannot be used with safety on corn. When used 

 as a spray, the usual dilution ranges from 6 to 10 pounds to 100 gallons 

 of water. 



Cryolite and other fluorine compounds sometimes cause injury when 

 applied to plants previously treated with soaps or with sprays con- 

 taining arsenicals. 



For the preparation of cryolite dusts, talc, clay, and sulfur may be 

 used, but not lime. Cryolite mixture is prepared at the rate of 40 to 

 60 pounds of the chemical to 60 to 40 pounds of the carrier. 



Caution. — Cryolite is a poison, and should be handled with care. 

 This is one of the fluorine compounds, and apples and pears con- 

 taining residues in excess of 0.02 grain of fluorine per pound will 

 be subject to seizure and destruction by health officials. 



CUBE 



See Rotenone-containing Roots (pp. 30-32). 



DERRIS 

 See Rotenone-containing Roots (pp. 30-32) . 

 DILUENTS OR CARRIERS 



The ideal diluent for an insecticide in the powder form is one which 

 is a suitable carrier for it and which functions satisfactorily in dusting 

 machinery. The diluent, to be a suitable carrier, must be such that 

 when mixed with the insecticide the two will remain as a homogeneous 

 mixture both before and after discharge from the duster, or until the 

 dust is deposited on the plant. It should also be compatible from the 

 chemical standpoint, that is. it should not cause an undesirable chem- 

 ical change in the insecticide with which it is mixed. The more com- 

 monly used materials listed below are all domestic products. 



Bentonite. — See page 6. 



China clay. — This material is also known as kaolin. It is a white, 

 residual clay, and as marketed it is not a definite chemical compound 

 but rather any one of several hydrated aluminum silicates. 



Diatomaceous earth and hieselguhr. — These materials may be white, 

 light gray, or pale buff. They are the siliceous remains of fossil 

 diatoms. 



