41 



quickly, it is very essential that the liquid be often and 

 thoroughly stirred. It is to be sprayed on the fruit trees 

 and other plants by means of some kind of force-pump and 

 hose with a spraying nozzle. (See machines for applying 

 Insecticides.) One should be exceedingly careful in spray- 

 ing peach trees not to get the mixture too strong, since the 

 leaves of this plant are very tender and easily "burned" by 

 Paris green or London purple. A mixture of one pound 

 Paris green to 250 gallons of water should be used on peach 

 trees, and that only when the leaves are young. Apple trees 

 should be sprayed just after the flowers have fallen. Small 

 fruits and vegetables are not easily injured, if at all, by 

 Paris green. Since Paris green is frequently adulterated, 

 it is advisable to test it before making any extensive appli- 

 cation. One sample of Paris green analyzed by the chemi- 

 cal department here last year was found to contain not a 

 trace of Paris green, nor even of arsenic or any other poison. 

 Some failures in the application of insecticides are due to 

 poor or adulterated material. 



Paris green or London purple may be mixed with Kero- 

 sene Emulsion in some cases, and thus an insecticide for 

 both biting and sucking insects is made. The great advan- 

 tage to be gained by this mixing is the time saved in making 

 one application instead of two. For details see under 

 Kerosene Emulsion. 



London Purple is about as good as Paris green as an 

 insecticide in many cases, and has this advantage, that 

 it is much cheaper, costing about fifteen cents per pound, 

 and is also a much finer powder and hence remains sus- 

 pended in water much longer. It is to be used in the 

 same way and in the same proportions as Paris green. 



Hellebore (white) is a powder poison made from a plant. 

 It kills both by being eaten and by contact. It can be 

 used as a powder to be dusted on to the plant either full 

 strength or diluted with flower, or as a liquid, one pound 

 Hellebore to 40 gallons of water, to be sprayed on the plant. 

 It costs about twenty-five cents per pound. It is used 



