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 insecticides on the harvested product may endan- 

 ger 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 applied 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 2 3 per pound, and for fluorine. 0.02 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 



