THE EOSE APHIS. 15 



TREATMENT IN THE GREENHOUSE. 



For the treatment of the rose aphis as it occurs in greenhouses the 

 nicotine solutions may be used, but at a lower strength than advised 

 in the preceding paragraphs. Conditions vary somewhat, but it is 

 believed that in most cases if the nicotine solution is used at the 

 strength of 1 part to 2,000 of water it will not injure the rose plants 

 if applied on a dark day or late in the afternoon so that the plants 

 will not be exposed to reflected sunlight through the glass. 



When greenhouses containing different forms of plants are syringed 

 with a forcible stream of water or with neutral soaps of the castile 

 or similar types for the red spider and other insects, the rose aphis 

 and other green aphides will also be killed. The same is true in 

 regard to fumigations with hydrocyanic-acid gas for other rose pests. 

 Directions for the use of hydrocyanic-acid gas for the fumigation of 

 greenhouses and cold frames are given in Circular No. 37 of the 

 Bureau of Entomology. In the experience of Dr. A. F. Woods, the 

 author of that publication, the young growth of roses is particularly 

 sensitive and has been more or less injured in experiments in the use 

 of this gas. This is particularly true of such varieties as "Perle des 

 jardins," "Mermet," and "Bride." 



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