3 
Part I.] Beeson : Life-History of Diapus furtivus, Sampson. 
in dying trees, and to what extent each species could be considered 
primary. All dying Sal, and all dead Sal which had died not more 
than six months previously, were thoroughly examined for insect work 
of all kinds. In the majority of cases, the trees were felled and barked 
for their whole length and the robots uncovered. When not felled, the 
trees were examined by climbing and partial barking. The following 
forests were visited and groups of sample trees taken in each. Jalpai- 
guri Division— Panjora, Khariarbander, Goramara, Apalchand, Katam- 
bari, Muraghat, Kuntimari. Buxa Division— Mendabari, Chilarpata 
Poro, Rajabhatkhawa, Raidak, Damanguri. The results of the enquiry 
are of interest, not only as determining the cause of mortality in Jalpai- 
guri and Buxa Divisions, but also as suggesting the probable relative 
importance of Sal-infesting insects as pests in normal Sal forests. 
The data obtained show that dying Sal trees are subject to the 
attack of some twenty species of bark and wood-boring beetles, generally 
associated in groups of three or four species,with a normal preponder¬ 
ance in number of one species over its associates. This may be attri¬ 
buted to the early arrival of one species, which is able to establish over 
the greater part of the bole before the swarming of the associated species 
occurs. The sample trees grouped, according to the prevalence of the 
more numerous species, give the following percentages :_ 
TABLE I. 
Incidence of species of* Sal Borers in Bengal, 1914-15. 
i 
Trees with insects absent at time of death . 
36 
2 
Trees with insects present at, or shortly after, death . 
• 
(a) 
Hoplocerambyx spinicornis, Newm. 
30 
1 
(b) 
Diapus furtivus , Samps. .... 
16 
(c) 
Xyleborus major, Steb. .... 
5 
(d) 
Either a, b, or c, associated with—- 
64 
Sphaerotrypes siwalikensis, Steb. 
Xyleborus fallax, Eichh. 
Xyleborus andrewesi, Bldfd. .... 
Platypus curtus, Chap. 
Diapus quinquespinatus, Chap. 
13 
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