208 The Principles of Vegetable- Gardening 



Insecticides 



Paris green, — The standard insecticide for all chewing or 

 biting insects is Paris green. This material varies considerably 

 in composition, and its price fluctuates; therefore many sub- 

 stitutes are in the market. Perhaps the best of the home-made 

 substitutes is the arsenite of soda and lime, which is described 

 below. Since Paris green may contain more or less soluble 

 arsenic, which is caustic to foliage, it is now the practice to add 

 lime to it, no matter on what plants it is used. Lime also makes 

 it adhere better. The ordinary strength is one pound of the Paris 

 green to 200 to 300 gallons of water. On potatoes and some 

 other plants, however, it may be used as strong as one pound to 

 100 gallons, particularly if lime is added. If the amount of lime 

 is one -half or one -third as much as the Paris green, it will be 

 sufficient to satisfy the chemical reactions ; but it is ordinarily 

 advisable to add as much lime as there is Paris green, in order to 

 increase the adhesive properties. Paris green mixes better with 

 water if it is made into a paste (by stirring it in a little water) 

 before it is thrown into the barrel. If it is put into the barrel 

 dry, much of it floats and does not readily incorporate itself with 

 the water. For potato bugs, it is sometimes sufficient to sprinkle 

 the Paris -green water on the plants ; but the best results are to 

 be secured only when it is applied with a pump and fine nozzle, 

 so, that the liquid is broken and driven to all parts of the plant. 



It is now customary to use Paris green in the Bordeaux 

 mixture, and thereby to combat both insects and fungi at one 

 spraying. The Paris green is added to the Bordeaux mixture as 

 if the Bordeaux were so much water. That is, if one desires to 

 use Paris green at the rate of one pound to 200 gallons, he adds 

 his pound of poison to 200 gallons of Bordeaux mixture. In this 

 case, of course, it will not be necessary to add lime to the Paris 

 green, since the lime of the Bordeaux mixture will answer all 

 requirements. Paris green is sometimes added to Bordeaux at 

 the rate of eight ounces to 50 gallons. 



London purple is often used instead of Paris green. It is 

 used in the same strengths and may also be added to the Bor- 



