644 Scolytus destructor attacks healthy Trees. 



same year ; being above two years after my publication ! It is, 

 therefore, needless for me to insult the intellect of your 

 readers, by pointing out the palpable absurdities and gross 

 misstatements of the writer, beyond what is above stated ; 

 sufficient has been given to show the animus which appears 

 to incite the writer to oppose, by garbled notices, what I have 

 remarked ; and the little reliance that can be placed on his 

 statements. — J. F. Stephens. Old Church House, Camberwell, 

 Oct. 31. 1836. 



Scolytus destructor attach healthy Trees. — In referring to 

 Mr. Denson's detailed account of that formidable insect the 

 Sc61ytus destructor of Olivier (IV. 153 — 156.), I am in- 

 clined to think he is mistaken, when he states that the insect 

 only attacks diseased or dying trees. He certainly appears 

 justified in that opinion by the experiment on the elm in 

 his garden ; but, in the parish in which I reside, I have 

 witnessed so many young and healthy elms perish from the 

 attacks of this insect, that I feel satisfied their ravages are 

 not confined to diseased trees alone. The churchyard of 

 Hackney parish was planted, about thirty years ago, with a 

 variety of forest trees, the greater part of the common elm 

 ( r/lmus campestris) ; and, until the last five or six years, they 

 throve, and promised to become, for many years, an ornament 

 to the spot ; but they then began to suffer from the Scolytus ; 

 and, out of probably a hundred elms, twenty have already 

 perished, and many others are so injured, that they cannot 

 survive another year. Any one who has observed these trees 

 (and there must be several among your readers) will, I am 

 sure, agree with me, that more vigorous trees could not be 

 found, previously to the attacks of the insect; therefore, I fear 

 the elm is subject to the ravages of this destructive insect 

 in every stage of its existence. The trees now infested 

 (Sept. 28.) have nearly lost their leaves ; and their trunks 

 swarm with flies and wasps, attracted to the banquet by the 

 saccharine juice they exude; as Virgil says of the oaks, 

 " Sudabunt roscida mella ; " while the uninvested trees have 

 their "green livery" as fresh as in July. Some persons have 

 imagined that gas escaping from the pipes has produced the 

 great mortality among the elms ; but, as they perish where 

 gas is far removed from them, this conjecture is untenable. 

 The writer of a Treatise on Ornamental Planting, published 

 by the Society for the Diffusion of Useful Knowledge, says, 

 in a note (p. 72. and 73.), that a tree of the Pin us Pinaster, 

 reared in a pot, was subjected to the influence of carburetted 

 hydrogen gas, by means of a pipe conducted to its roots, 

 without producing any perceptible effect. Fabricius calls this 



