Part V.] Sweet: On Air Seasoning of Indian Timbers. 
85 
2. Flat-headed Borers (BuprestidaeJ. 
The grub of the Buprestidae is flattened and tape-like in comparison 
with that of the previous group, and its tunnels are consequently very 
much narrowed on the shortest diameter. The workings extend 
irregularly in the sapwood, and deep into the centre of the log in 
timbers with no marked heartwood ; they vary much in width owing 
to frequent alteration of direction .and are characteristically packed 
tightly wth wood-dust. In this class there is a tendency for develop- 
ment of annual cycles to be delayed to 18 or 24 months, with conse- 
quent extension of the injurious period, e.g. : — 
Acrocarpus fraxinifolius by Belionota prasina; Pinas longifoliu by 
Ancylocheira geometrica. 
3. WEE7ILS (Curculioiiidae). 
The larger weevil grubs' make straight or curved circular tunnels 
up to f" diameter, that run horizontally across the bole and are 
normally empty of dust or fibres. The small species extend tunnels 
wide and over in more or less radial directions, e.g. : — 
Pinas Khasya, Ptemcarpus indicus, Kydia calycina by Sipalus 
spp. 
4. Brenthidae, Lymexylonidae, Siricidae, etc., and other families 
make elongated galleries in horizontal planes varying in size from 
small shot to S. S. G., e.g. : — 
Bombax malabaricum by Cerobates tristriatus ; Pleritiera Fomcs 
by Xiphydria lieritierae. 
5. Shot-hole and Pin-hole Borers (Platypodidae and XyleborinaeJ. 
As their name implies borers of this group make holes of the size 
of a pin up to that of large shot. The tunnels are constructed in 
horizontal planes and run parallel with the circumference and occasion- 
ally branch. In trees with well-marked heartwood the inner tunnels 
rarely penetrate more than an inch or tw'o into the heart, but in un- 
diSerentiated timber they extend throughout the log. The tunnels 
are empty of wood-dust and the wood near to them is often stained 
black. Unless very heavily infested the structural value of the timber 
is not affected by the work of this group, although its appearance is 
spoiled for certain uses. e.g. : — 
Shorea robusta by Diapus furtivus; Odina Wodier by Platypus 
solidus; Pterospermuin acerifolium by Xyleborus perforans, 
but scarcely any timber trees of importance are immune 
from attack by Platypodidae. 
6. Sapwood Borers (numerous families). 
By far the largest group of borers is that in which the grubs 
-excavate tunnels on the surface of or just within the sapwood, for the 
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