79 
Part III.] Beeson: BeeKole Borer of Teak. 
them in order to obtain points for the construction of the girth-beehole 
curve. The girth of a typical mean 20 year-old tree is 26‘7 inches and 
the beehole index for a tree of this girth according to the curve is 4*2 ; 
as this amount is supported by the figure for the arithmetic mean, this 
value may be taken as approximately correct. It is slightly below 
the average for plantations of this age. 
The following table gives the annual incidence in the dateable trees. 
Table 21.— Annual Incidence in a 20 year-old Plantation, Kaing 
Reserve , Pyinmana, 1919. 
899—1903 
o 
a 
05 
1 1903 
1 
I> 
o 
05 
1938 
J 6C6X 
O 
05 
tH 
IT6I 
<M 
05 
1913 
1914 
1915 
1916 
1917 ? 
1918 
Total. 
Combined Attack, 
6 Trees . 
0 
i 
1 
1 
1 
4 
2 
3 
4 
4 
3 
2 
2 
1 
7 
34 
Reduced values. 
|o*13 
•• 
0-13 
•• 
0-52 
0*20 
0-39 
0-52 
0-52 
1 o 
03 
_ o _ 
o 
1 CO 
i_6 
1 
0*26 
1 
0-13 
0*92 
4-2 
Although the past history of this plot and the previous plot with 
reference to fires and thinnings is similar yet the behaviour of the 
incidence curve is on the whole dissimilar. The number of sample 
trees taken is too small to decide if the difference is real or due to insuffi¬ 
cient sampling. 
Other Localities. —Mr. Unwin found the borer present in 1916 
in plantations around Mohnit, Taikma and Nganzat, Kaing Reserve, 
especially in the 1905 plantation at Taikma and the 1893 plantation 
at Nganzat. 
3. Incidence in Natural Forest. 
On the high ground between the two plantations is a group of teak 
of similar size and development; one of these (S. T. 17) was felled and 
analysed. Girth 41 inches ; age approximately 70 years ; fairly evenly 
grown with only one short (6 years) period of suppression. Total 
number of beeholes 8, their dates as under :— 
Table 22. —Annual Incidence in a 70 year-old Natural Teak , Kaing 
Reserve, Pyinmana, 1919. 
1848-1866 
1867 
1868 
1869 
1870 
1971-79 
O 
00 
GO 
1881—I839J 
1890 
10 
O | 
05 
l ! 
0D 
9061 
1907—1912 
1913 
C5 
7 
05 
00 
05 
0 
1 
1 
0 
1 
0 
1 
0 
1 
0 
1 
0 
1 
0 
! l 
[ 307 ] 
