186 Mode of destroying the White Scale 



Art. VIII. On destroying the White Scale on Pine- Apples ^ together 

 with some Remarks on the Natural History of that Insect. By 

 J. B. W. 



The pine-apple plant, when cultivated in the hot-houses of 

 this country, is subject to the attacks of three species of insects, 

 known by gardeners as the brown scale, the white scale, and 

 the mealy bug. Of these, the brown scale is comparatively 

 harmless ; the mealy bug, too, although extremely unsightly, is 

 by no means so injurious to the health of the plants it attacks 

 as the white scale. Beneath the latter, there is always a small 

 speck upon the leaves, quite divested of the usual green colour, 

 and, apparently, of life. When, therefore, the insects become 

 numerous on a plant, which soon happens after it is once fairly 

 infested, as each of them destroys a part of its vitality, it might, 

 perhaps, in so far as regards injury to the vegetable economy, 

 be fairly compared with one in whose leaves a like number of 

 small holes had been punched. But it is not clear whether this 

 deprivation of vitality ought to be attributed to the abstraction, 

 by the insects, of thejiiices which sustain life; or to the de- 

 struction of the sap- vessels of those parts of the leaves they cover 

 and feed upon, or to both these causes combined : nor, indeed, 

 would a knowledge of the precise manner in which the mischief 

 is done be of any assistance in the destruction of an enemy 

 which, insignificant as it seems to those who are unacquainted 

 with its powers of endurance, generally proves the conqueror. 



Of all the various remedies hitherto recommended for the era- 

 dication of the white scale, not one, I believe, has been found to 

 effect the desired end with certainty, in consequence, as it ap- 

 pears to me, of their having been improperly applied. A slight 

 glance at the economy of this insect, securely protected by a 

 waterproof coat, is sufficient to show the uselessness of attempt- 

 ing to kill it by any kind of wash, unless, indeed, it were some- 

 thing of a powerfully caustic quality, which, most likely, would 

 make an end of both insects and plants. 



So long as the scale adheres to the plants, it may be accounted 

 invulnei'able, and it might be laid down as an unexceptionable 

 rule, that no recipe ever has succeeded, or ever will succeed, 

 which does not strictly enjoin the removal of every insect pre- 

 viously to the application of the ingredients. Upon this rule the 

 following remedy is founded; and having been witness to two 

 successful trials, one of which was made upon plants under ray 

 own care, I can most confidently recommend it. For a know- 

 ledge of it, I am indebted to Mr. John Wilson, gardener to the 

 Rev. H. Pemberton, Church Stretton, Salop ; and, although I 

 am not authorized by Mr. Wilson thus publicly to mention his 



