74 
Indian Forest Records. 
[Vol. VIII. 
(excluding tree No. 14) is 39*8 years. Plotted as a girth-beehole graph 
the data in Table 16 give a rather steep curve [See Girth-Beehole 
Incidence Graphs], but its upper limits fall between those for the Pyon- 
chaung plantations of comparable ages, and it may be accepted as 
approximately correct. Of the 603 beeholes examined only 258 are 
definitely dateable ; the mean age of the dateable trees is 40 years and 
their mean girth 36 inches. The beehole-value for a girth of 36 inches 
is 42. The mean girth of the trees 40-42 years old (containing 140 
beeholes) is 34'4 inches and the beehole value derived from the curve is 
39. The index of attack in this area is therefore between 39 and 42 
beeholes in the mean tree. 
Annual Incidence. 
A large proportion of the sample trees was found after billetting to 
show zones of suppression at various periods, and accurate dating of 
only 42‘8 per cent of the beeholes was possible. The following table 
shows the annual frequency of the attack in the 7 dateable trees :— 
[ 302 ] 
