970 Transactions.— Zoology. 
description given to me I suspect the so-called grub to be the larva of our 
largest longieorn beetle, Prionoplus reticularis, which I know passes three 
or four years of its existence in the larval state, in logs of various trees. 
The investigation I have bestowed upon this subject within the last two 
years clearly establishes the value of the gum as a temporary protection 
against the attacks of indigenous Coleoptera, which would, but for its 
presence, inflict an incaleulable amount of pecuniary injury, not only on 
owners of Kauri forests, but also on whole communities engaged in the pre- 
paration of this timber for use in a variety of manufactures. 
I now present to the Institute, specimens of the beetles adverted to in 
this paper, and as pieces of logs in the damaged conditions specified, will 
serve more fully to illustrate the subject, I now deposit in the Museum the 
piece of a board sawn out of a Kauri log, showing the injury done by Xenoc- 
nema spinipes, as also a small portion eut from another log as an example 
of that inflicted by Dryoptherus bi-tuberculatus. 
When visiting localities which were being denuded of this valuable tree, 
the conviction was at once forced upon me that the practice which obtains 
of selecting the bole of the tree only for use involved a serious loss, but a 
consideration of the cireumstances compels one to admit that the remainder 
of the tree cannot be profitably utilized either for fencing-posts or firewood, 
unless a forest has convenient water-carriage, or is so situate that inexpen- 
sive bush-tramways could be constructed to a point within easy reach of a 
good market, but if colonial agriculturalists were more cognizant of their 
real interests, they would devise means for converting the refuse timber, 
not only into a valuable ingredient of the manure heap, but even of the soil 
itself. 
The money so often lavishly invested in the purchase of foreign guano 
might be much more beneficially employed in reducing the waste timber to 
charcoal, which, by its remarkable property of condensing and absorbing 
ammonia, would fully answer the purpose of ammoniacal manure, particu- 
larly on most of the clay lands that so often refuse to yield more than a 
scanty crop. Moreover, it has been incontestably proved that charcoal 
induces healthy growth in diseased plants. 
Were farmers to satisfy themselves by experiments on a small scale, 
such as adding this substance to one part of a manure heap, and leaving the 
remainder to be deprived of its most useful gases and liquids as is usually 
done, and then use the two portions separately, the results would be so 
obvious that further action in the matter might be safely left to them. 
Tf steps were taken for utilizing the timber now allowed to decay, the 
saw-dust produced at the mills ought also to be eharred—an operation 
which could be readily effected by any intelligent engineer, by constructing 
