INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 1] 
Chloropicrin may be purchased in 1-pound glass bottles or in ayn 
ders of from 1 to 100 pounds capacity. 
CRYOLITE 
Cryolite, or sodium fluoaluminate (Na;AIF,), 1s a white crystalline 
chemical. Both natural cryolite imported from Greenland and 
synthetic materials of similar composition are available, and for 
most uses there is little difference between them. Large quantities 
are used in the control of the codling moth on apples in the semiarid 
valleys of the Pacific Northwest. Cryolite is also used for the 
control of the sugarcane borer, the tomato pinworm, the tomato 
fruitworm, the lima bean pod borer, the corn earworm and the Mexi- 
can bean beetle on beans, the apple flea weevil, the walnut husk fly, 
the pepper weevil, cabbage caterpillars, blister beetles, and flea 
beetles. 
As a dust undiluted cryolite may be applied, but it is usually 
diluted with talc, pyrophyllite, or sulfur to contain from 40 to 70 
percent of sodium fluoaluminate. As a spray it is used at the rate of 
3 to 121% pounds per 100 gallons of water, often with a small quantity 
of mineral or fish oil to improve its adhesiveness. 
Cryolite should not be mixed with lime. It cannot be used with 
safety on corn or grapes, and it may cause injury to apples in the 
East and Middle West. Cryolite sometimes causes injury when 
applied to plants previously treated with soaps or with sprays 
containing arsenicals. 
Caution.—Cryolite is a poison, and should be handled with care. 
This is one of the fluorine compounds, and the Federal tolerance 
for fluorine for apples and pears is 0.05 grain per pound of fruit. 
CUBE 
See Rotenone-containing Roots (pp. 30-32). 
DERRIS 
See Rotenone-containing Roots (pp. 30-82). 
DICHLOROETHYL ETHER 
Dichloroethyl ether, at the rate of 2 percent by volume, is used as a 
substitute for pyrethrins in highly refined white miner al oil for in- 
jection into the silks of sweet-corn ears for prevention of earworm 
infestation. It is a colorless liquid that mixes readily with mineral 
oil when shaken or stirred thoroughly. It is not so satisfactory as 
oleoresin of pyrethrum for use in earworm oil, because at comparatively 
low temperatures it sometimes fails to evaporate completely from the 
ears before they are used for food and thus may impart an undesirable 
flavor tothem. (See Pyrethrum, or Insect Powder, pp. 29-380.) 
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. 
