CHAPTER XXV. 



INSECTS OF THE GREENHOUSE. 



Few of our greenhouse plants are free from the 

 attack of insects, and many of them are greatly injured 

 by parasitic fungi, so that constant watchfulness is 

 necessary if they are to be kept in a healthy condition. 

 In this chapter we shall describe some of those that are 

 most troublesome, and give remedies for their destruction. 

 It should be mentioned, however, that if proper care is 

 given to the selection of the stock from which the plants 

 are propagated, and if attention is paid to providing 

 them with suitable soil, a congenial temperature and the 

 necessary amount of water and fresh air, the plants will 

 not only be more likely to escape attack, but will be 

 much less injured if the insects and diseases appear. 



It will be found that the fungicides are for the most 

 part intended for use as preventives rather than cures, 

 and to be effectual will need to be applied before the dis- 

 ease has any hold upon the plants. The same thing 

 is true with many of the insecticides, to the extent that 

 they are most effective before the insects have reached 

 their full development. Another reason for the early 

 application of the remedies against both insects and dis- 

 eases is that they multiply very rapidly and if not checked 

 at the start they may propagate and become so numerous 

 that much harm may be done. 



In making a choice of insecticides, we should be 

 guided by the nature of the insect for which it is to be 

 used. Thus against many insects that take their food 

 by biting off and chewing the leaves, the arsenites, such 



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