1870. ] 1038 
ON THE HABITS OF PLATYPUS CYLINDRUS, FAB. 
BY T. ALGERNON CHAPMAN, M.D. 
This beetle has been well described by Ratzeburg in his “ Forst- 
insecten,” and the larva is well described and figured by Perris ; but 
neither of these authors gives much detail as to its habits, or, indeed, 
appears to have met with it in sufficient abundance to make many 
observations with regard to those habits. 
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. These burrows, in which 
both perfect insects and larve 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 larva and perfect beetle,—presenting no 
narrow burrows of young larve, as observation of most of the other 
Xylophaga would have led us to expect. And the inhabitants are not 
confined each to its own branch of the burrow, but the larve, 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 
asiding. 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 difficulty of tracing the proceedings 
of the insects in the centre of the solid masses of oak they inhabit. 
The usual habitat of Platypus 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 afterwards 
looking 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. 
After a brood, or rather colony, has been reared in one part of a 
stump, another part which has meantime reached the proper condition 
is often attacked in the following year, so that it may happen that one 
part of a stump is quite rotten, whilst another is still tenanted by the 
beetle ; but, wherever there are larve still feeding, the wood continues 
apparently sound. 
