52 State H orticultiiral Society. 



and it is owing to ignorance on this point that nine-tenths of the fail- 

 ures in spraying occur. 



There are two different ways to determine whether an insect is 

 biting or sucking. You can look at the mouth parts of the insect, and 

 provided you have a sufficient knowledge of insect anatomy, you can 

 determine without much difficulty whether the insect be a biting or a 

 sucking one. The best way, however, for the ordinary fruit grower to 

 determine this question is to examine the parts of the plant that are in- 

 jured by or are infested with the particular insect. If the parts of the 

 plant are removed, that is, if holes are eaten in it, or otherwise removed, 

 one may be sure that he is dealing with a biting insect, which has eaten 

 away the tissue and swallowed it. If, on the other hand, no tissue 

 seems to be removed, one can be reasonably certain that the insect caus- 

 ing the injury is a sucking insect, which has simply pierced the tissues 

 of the plant with its beak and extracted the sap. 



Where an insect has biting mouth parts and eats away a portion of 

 the plant, we can kill that insect by placing on the plant some kind of 

 an arsenical poison, which, as long as it remains there, will kill any or- 

 dinary insect that may eat of the plant, and in so doing, swallows 

 a trace of the poison. 



On the other hand, a sucking insect will stick its beak through any 

 amount of poison we may put on a plant and into the tissues and extract 

 the healthy sap without getting any poison whatever. Hence, you can 

 readily see the necessity of determining whether the insect has biting or 

 sucking mouth parts, otherwise one is apt to use an arsenical poison for 

 a sucking insect, in which case no harm whatever can come to the insect 

 itself. 



For biting insects I would advise the use hereafter of arsenate of 

 lead, which you can make yourself, or can purchase on the market under 

 the name of "Disparene." If you have a small amount of spraying to 

 do, you can perhaps buy Disparene more cheaply than you can go to 

 the trouble of making it, but if you have a large amount of spraymg to 

 do, it will save you money to make your own arsenate of lead, which 

 can be done in the following way: 



Dissolve in a half bucket of water four (4) ounces of arsenate of 

 soda and in another half bucket of water twelve (12) ounces of acetate 

 of lead. Both these substances can be purchased from the leading 

 chemical firms and should be obtained in as pure a state as possible. 

 Chemically pure substances are preferable ; the ordinary commercial 

 chemicals will not answer, as a rule. After you have dissolved each of 

 these substances separately in the half buckets of water, turn the two 



