INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 3 
under lock, and well out of reach of children and others unfa- 
miliar with their poisonous nature. Every effort should also be 
made to prevent domestic animals and livestock from being poi- 
soned by insecticides, either through feeding on treated vegeta- 
tion, licking containers, or drinking water which may have been 
contaminated. 
To aid in avoiding poisoning from the accidental use of white 
insecticides, some of them, particularly lead arsenate, calcium 
arsenate, and sodium fluoride, are now colored by the manufacturer. 
Containers in which materials are being mixed or batches of pre- 
pared insecticides set aside for the moment should not be left open or 
exposed in such a way that roaming farm animals, in passing, can lick 
them. Empty packages and bags should be buried or burned. Un- 
used portions or discarded material should be buried at least a foot 
below the surface and away from water supply or drainage. Horses, 
cows, sheep, and poultry should be prevented from feeding or grazing 
under trees that have been sprayed. Water from roofs that have been 
sprayed accidentally may also be a source of danger. 
SPRAY RESIDUES ON PLANTS 
Residues of certain insecticides on the harvested product may 
endanger the consumer’s well-being and must be guarded against. 
The recommendations that follow are given as a guide in avoiding 
such risks. 
Inorganic insecticides, such as the arsenicals and fluorine compounds, 
should not be sprayed or dusted on the edible foliage or fruit when 
the residues on the part used for food cannot be removed, either by 
washing or wiping, or by stripping off the outside leaves. These 
materials should not be appled to strawberries within 3 weeks of 
harvest, or to grapes and bramble fruits after the blossoms have opened 
and the berries have begun to form. Treatment after such time may 
leave dangerous quantities of residues on the harvested berries. 
Fruits such as apples may be washed in weak acid or alkaline solu- 
tions to remove excessive deposits. Unless they are to be washed in 
a manner that will remove excess amounts of insecticides, apples should 
not be sprayed with arsenicals or fluorine compounds after June. 
The Federal Government prohibits the movement and sale of apples 
and pears in interstate commerce when residues of lead, arsenious 
oxide, and fluorine exceed certain prescribed limits. For lead the 
tolerance is 0.05 grain Pb per pound of fruit, for arsenic, 0.025 grain 
As,O,; per pound, and for fluorine, 0.05 grain F per pound. 
Insecticidal residues cannot be removed satisfactorily from cabbage, 
lettuce, celery, spinach, cauliflower, turnip greens, kale, broccoli, or 
other greens by a superficial washing of the head or leaves. Such a 
washing may remove the residues from the outside smooth surfaces of 
the leaves or fruit, but the innermost parts among the folds or ribs 
will not be affected materially. 
Cabbage.—Such materials as paris green, cryolite, and calcium 
arsenate should not be applied to any portion of the cabbage plant that 
is to be marketed. This means that cabbage intended for marketing 
as U. S. Grade No. 1 (which allows four loose outer leaves) should 
