DISEASES AND INSECTS ATTACKING THE KOSE. 141 



tion. The most effectual is smoking with sulphur, dusting 

 with dry tlowers of sulphur, or syringing with sulphur wa- 

 ter. The former should only be practiced by a skillful 

 liand, as too much sulphur-smoke will sometimes entirely 

 kill the plant. 



Mould is due to a minute gray fungus, Peronospora 

 sparsa, and manifests its presence by the appearance of 

 irregular pale brownish spots upon the upper surface of 

 the leaf Upon the under surface of these spots the 

 mould will be found. 



Other species of fungi attack the Rose, but they are 

 not sufficiently troublesome to the cultivator to need 

 enumeration here. 



The 2?isects which infest the Rose are quite numerous, 

 and their attacks are more or less injurious. The majority 

 of those which are found on the plant in the state of per- 

 fect insects are comparatively harmless. The most in- 

 jurious are those whose larvae feed on the leaves and pith 

 of the trunk and limbs, and thus destroy the plant; while 

 the perfect insect, like the Green-fly, will simply stop the 

 growth and impair the health of the tree, by fastening up- 

 on the green and tender bark of the young shoots, and 

 devouring the sap. It is highly desirable that amateur 

 cultivators should devote more time to the study of Ento- 

 mology, for upon an intimate acquaintance with the hab- 

 its of these minute depredators depends, in a greater de- 

 gree than is generally supposed, the success of cultivation. 

 Our own leisure is so limited, that we have been able to 

 devote very little time to this subject; and we can find 

 no work that treats in detail the insects that attack the 

 Rose. We simply give some account of the most trouble- 

 some ones drawn mainly from Harris' Insects Injurious to 

 Vegetation. 



Green-Fly, or Plant-Louse. — Aphis Bosm. — This very 

 common insect is a scourge to roses, from the facility of its 



