318 STATE HORTICULTURAL SOCIETY. 



So far as the kind of insecticide to be used is concerned, we may group 

 the insects into two classes, (1) those that eat their food, and (2) those 

 that have special organs by which it is sucked up. The arsenites will have 

 no effect upon the insects of the second group, but, with very few exceptions, 

 they can be used with certainty against those in the first, provided they 

 can be distributed so that the insects will take them in with their food. 



PARIS GEEEN AND LONDON PURPLE. 



The two forms most commonly used are, Paris green or arsenite of 

 copper, and London purple or arsenite of lime; the latter is light, and is 

 easily suspended in water, requiring much less attention in stirring than 

 Paris green to keep it from settling, and on the other hand it is more 

 readily soluble in water, and is more likely to burn tender foliage. The 

 reverse of this, however, is true when combined with ammonia contain- 

 ing fungicides. 



For all large trees, they are used in water at the rate of one pound to 

 from 200 to 300 gallons, but, for some of the vegetables and small fruits, it 

 is perhaps preferable to use them as a powder, at the rate of one pound to 

 from thirty to one hundred pounds of plaster, or Hour. 



For the apple, and, in fact, for all of the fruits and vegetables with 

 thick, rough leaves, the use of one pound to 200 gallons of water is none 

 too much; but for the peach and similar trees, it should never be over one 

 pound of the poison to 300 or 350 gallons of water, and, after the first of 

 July, even this will be found too strong. 



In addition to the potato beetle mentioned above, the arsenites are used 

 largely as remedies for the codlin moth, plum curculio, cherry slug, cur- 

 rant worm, and hundreds of other leaf-eating insects. 



Whether applied as a powder, or in water, an attempt should be made te 

 reach, with the poison, every part of the plant, and for this reason a bel- 

 lows or pump, that throws a fine powder or spray with considerable force, 

 is desirable. In the use of liquids, the spraying should be kept up until 

 every part has been touched and the plant begins to drip, and it should 

 then be discontinued. The same rule applies to other insecticides and to 

 all fungicides. 



INSECTICIDES FOE SUCKING INSECTS. 



In addition to the large class of insects that obtain their food by means 

 of jaws, there is another that has its mouth parts modified into a tube, 

 through which it sucks the juices of plants and animals. Such insects 

 •can not be poisoned by arsenites, and some insecticide must be used that 

 will kill by contact. The simplest and best is known as 



KEEOSENE EMULSION. 



The formula recommended by Prof. Cook has proven very satisfactory, 

 and is as follows: Dissolve \ pound of hard soap in two quarts of boiling 

 water, add 1 pint of kerosene and mix thoroughly. This should form a 

 thick, cream-like mass. Before using, it should be diluted to two gallons, 

 with water, for most plants. For plants with tender foliage, like the 

 squash, this will prove too strong, and in such cases, various strengths 

 should be tried, until one is found that will not injure the plant, and yet be 



