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ON THE HABITS OF PLATYPUS CYLINDRUS— Fabr. 

 By T. ALGERNON CHAPMAN, Esq., M.D., Abergavenny. 



This beetle has been well described by Ratzburg in bis " Forst-insecten," 

 and th« larva is well described and figured by Ferris, but neither give much 

 detail at to its habits, and do not, indeed, appear to hare mot with it in sufficient 

 abundance to make many observations with regard to them. I have thought, 

 therefore, that the following account of it, founded on observations made two 

 years ago, when I was studying the Xylophaga — some of them confirmed by fur- 

 ther investigation — might be of sufficient interest to be worthy of being read 

 to the Woolhope Club. 



Platypus Cylindrus burrows into the solid wood, and, in consequence, is 

 rather difficult to observe ; the gnarled texture of a solid and by no means 

 rotten oak stump being a most unpromising material to slice up in order to expose 

 the burrows of the beetle, as desired. Its history, however, presents several 

 points of much interest. The burrows, in which both perfect insects and 

 larvse are found, have always an extremity open on the side of the stump. They 

 are of uniform diameter throughout, viz., that of the full-grown larvae and per- 

 fect beetle, presenting no narrow burrows of young larvae, ai the observation of 

 most of the other Xylophaga would have led us to expect. And the inha- 

 bitants are not confined each to its own branch of the burrow, but the larvae, to 

 the number of from sixty to a hundred, together with the perfect beetles, 

 their parents, run actively backwards and forwards in the burrows, and from 

 one branch to another, getting out of each others way, backing into a branch to 

 let another larva pass, just as a train is shunted into a siding. The following 

 observations leave untouched several points in the history of Platypus which 

 I should have liked to have cleared up, for which my excuse must be the diffi- 

 culty of tracing the proceedings of the insects in the centre of the solid masses 

 of oak they inhabit. 



The usual habitat of Platypus Cylindrus is in oak stumps, but I have 

 met with it also in beech. After a tree has been cut down, although the stump 

 may throw up no shoots, it yet maintains for a time a sort of life ; portions of 

 bark, for instance, even two or three years after, look much like that from a 

 living tree. It is in such stumps that Platypus makes its burrows, and in those 

 parts of them which, though to all appearances sound, have, one or more years 

 after the fall of the tree, entered into the first stage of decay. What appears 

 to be essential is the presence in the wood of a certain fungus which probably 

 lives in the fermenting and decomposing sap. I shall recur to this fungus 

 when mentioning my observations on the young larva of Platypus Cylindrus, 



