208 DISEASES OF THE ROSE. 



iw, a designation which gives a perfect idea of the manner in which the saw-fly 

 destroys roses. 



Whatsoever may be the species of saw-fly which gives birth to the Excavating 

 worm, a point on which there is not yet sufficient knowledge to pronounce with 

 certainty, its ravages are prodigious, and now well known. 



As gardens are more exposed to the sim, more airy, less shaded, the rose-trees 

 are less injured by this larva. At Paris, most of those pertaining to particular 

 mansions are very much troubled, and mine among the number. Among those 

 connected with the monuments of the capitol, " Le Jardin des Plantes" is most 

 noted for its damages — next after it, the " Luxembourg" and the " Palais Royal." 

 The " Tuilleries" suflers least. In these large establishments, not much, if any 

 attention, is bestowed on it, so trifling comparatively is the injury. 



Our false caterpillar attacks the four-season rose-tree more particularly ; the 

 Centifolia, whose sprouts are large and tender ; the Pompon, etc. : the later roses, 

 as the Provence, the Frankfort, etc., are less subject to it. Those grafted on high 

 trunks, especially the Bengals, so abundant in the gardens at this day, resist this 

 injury better, on account, either of the greater solidity of their tissue, or their 

 sprouting later in the season. The moss-rose, and the thorny or pimpernel rose, 

 are rarely molested ; because the fly cannot easil}' find footing to introduce her 

 saw. It is the same with rose-trees well provided with vine-fretters, although 

 the shrub does not gain much by it, for these small animals destroy, in their way, 

 the roses on the peduncle, by heaping themselves upon them. 



As this larva is not seen much over a month, the remontant or perpetual roses 

 are found not to be injured by it at all. Thus the monthly, or four-season rose 

 sprouts the second time, while the centifolia not blooming again, does not possess 

 the same advantage. 



The damage consists, as I have already stated, in the destruction of the centre 

 of the young sjffouts of the rose-tree, thus depriving them of the organs necessary 

 to their growth. The ravages of this enemy cause the sprouts to" wilt and droop 

 towards the earth, and its presence can be thus detected. I have sometimes seen 

 the whole rose-tree thus aflected. More than three-fourths of the sprouts of those 

 in the free soil of my garden have been destroyed in this way within foui- years, 

 and all the means used were ineffectual to keep the insects away. 



I used various methods in succession, with the hope of finding a remedy for this 

 disaster. I endeavored to destroy the nymphs or chrysales, before their hatching, 

 thus : 1st, I scraped, rubbed: brushed, washed, etc., the trunks of my shrubs, believ- 

 ing, as some authors also do, that the saw-fl}"^ deposits its eggs in the wrinkles or 

 crevices of the bark, as it is the nature of some tenthreds, and all in vain ; in fact, 

 all my examinations with a magnifying glass have not enabled me to discover a 

 single egg on the bark of my rose-trees : 2d, I have cut ofi" at the surface of the 

 ground in the latter part of the season, these same trunks, with the same idea ; 

 and these animal devastators have yet excavated the peduncles of my roses : 3d, 

 I have ploughed, dug, and turned up the earth at the foot of my rose-trees before 

 the hatching of the nymphs of the saw-fly, in the hope that they would be laid 

 there when the worm should let herself down upon the ground, and be killed by 

 this overturning process, but without efiect : 4th, I have placed at the foot of rose- 

 trees: animal carbon, a bitter substance, composed of pungent and stinging mate- 

 rials, without any favorable result. 



All these attempts at destruction are entirely useless, when the fly has hatched 

 and deposited her larva in the young sprouts. We should then seek to destroy 



