Entomoloijical Sociely, 



6119 



been at the writer's elbow even while he held the pen, and dictated what he wrote: 

 before Rusticus, Kirby and Spence seem to have been cognizant of its doings; and to 

 go back still further, the very name carries with it an idea of some knowledge of its 

 economy. Captain Cox has, however, added one most interesting fact overlooked by 

 previous writers : that ' the female dies at the entrance of her tube, thus performing a 

 maternal duty by closing the aperture to her young ones with her own dead body.' 

 The |)oints, however, on which T would solicit for the Society additional information 

 are these : Captain Cox states his firm conviction that healthy trees are attacked by 

 Scolytus ; and that this insect is the cause of premature decay and eventual death. 

 He narrates with great perspicuity that eighteen dying elm trees were placed at his 

 disposal, that he experimented on every one of them, by taking off the surface bark 

 with a draw-shave; and that seventeen out of the eighteen completely recovered : the 

 the operation is most simple, and I believe every one will admit that its very simplicity 

 adds to its beauty and its value. Before commencing his experiments, Captain Cox 

 numbered the trees from 1 to 18, and made a careful memorandum of the state of each ; 

 the summary of these memoranda may be thus briefly staled. Fifteen were suffering 

 severely from the ravages of Cossus liguiperda ; and out of these fifteen, nine were 

 also infested with Scolytus : three, making up the eighteen, were attacked by 

 Scolytus, but all these three " slightly." Now, to a superficial observer, it will occur 

 that the state of the trees, scarcely bears out the author's own conclusion as to Scolytus 

 attacking sound trees, since fifteen out of the eighteen were manifestly attacked by 

 the most deadly enemy that a timber tree can possibly have : and to a superficial 

 observer, I purposely repeat this qualifying expression, nothing can present a more 

 sickly or abnormal appearance than a tree, the solid timber of which is riddled 

 through and through by the enormous larvae of Cossus liguiperda : such trees, with 

 or without the smaller pest, I should have unhesitatingly pronounced in an unhealthy 

 state. When Captain Cox favours us, as I doubt not he will, with an explanation of 

 this apparent inconsistency, arising probably from some accidental oversight or trans- 

 position of words, may I ask him to reexamine the larvae which he denominates those 

 of Cossus ligniperda, and which had so severely injured the fifteen trees under con- 

 sideration ; because I never happened to find that insect feeding on elm, and had not 

 the statement been made by an entomologist who possesses an unusually extensive 

 knowledge of the larvae of our British Lepidoptera, I should have fancied that 

 the trees were dying from some other and undiscovered cause. One other slight diffi- 

 culty occurs to me which will, doubtless, be removed without causing any additional 

 or unnecessary trouble to Captain Cox. Seeing that the larva of Cossus mines 

 the solid wood, and not the bark, except in its very juvenile state; and seeing that the 

 fifteen Cossus-mined trees completely recovered after their outer bark had been merely 

 draw-shaved, how is it to be explained that this simple external process affects 

 the deadly Cossus deep in the interior The author has not explained this, 

 probably concluding that entomologists were more intimately acquainted with the 

 reciprocal offices of bark and solid wood, than I fear is the case. I trust that 

 these queries, unimportant in themselves, will not be deemed irrelevant, but will 

 acquire some importance from the acknowledged importance of the subject ; I hope 

 they will induce Captain Cox to enrich our ' Proceedings' with a second paper still 

 more explanatory than the first. As an observation on Scolytus, quite independent of 

 the paper lo which I have been alluding, it is rather interesting that in the two great 

 liondon colonies of this insect, Greenwich Park and Cumberwcll Grove, its advent 



