INSECT PESTS AND DISEASES. 149 



Mr. Wise, of Toddington, says : " Paris Green is the 

 only thing which \ve have found really efficacious. For 

 plums, the pi^oportion is 1 oz. to 10 gallons ; and for apples, 

 1 oz. to 20 gallons. We have also used the former strength 

 for currants; but as the foliage is within the last few 

 days becoming so much stronger, we have been using it 

 at 1 oz. to 8 gallons. Neither of these solutions has 

 damaged the foliage, but killed the caterpillar." 



London Purple. In the past season, some amount of 

 trial was also made of another arsenical insecticide, which 

 has long been used in America, known as London Purple. 

 The purple may be used either as a powder dressing, or 

 it may be mixed with water and flour, and sprayed on the 

 trees just in the same way as Paris Green ; but owing to 

 its lightness a smaller quantity by weight of the purple 

 will treat a given number of trees than would be required 

 of Paris Green. 



Other desirable points are its greater diffusibility in 

 water, also its greater adhesiveness to the foliage, and 

 also that this purple or arsenite of lime is not so poison- 

 ous as the green or arsenite of copper, although, like the 

 green, the purple is a strong poison, and should be 

 treated and used with the same precautions and care as 

 the Paris Green. 



We have used at our nurseries and fruit plantations 

 both the Paris Green and London Purple, and although 

 we had a bad attack of the caterpillar, by the persistent 

 spraying we have very largely mastered the plague. But 

 we in common with many others did considerable damage 

 to the foliage by the application of the poisons. 



We believe, however, that the damage was chiefly due, 

 firstly, to want of knowledge as to the proper strength 

 to use with safety ; and, secondly, to the absence of 



