44 
Indian Forest Records. 
[Vol. vii. 
From Table 20 it will be seen that emergence of the first generation 
commenced on the 8th April and that of the second generation concluded 
on the 5th June. The maximum emergence periods occur from the 
11th April to the 25th. April, and again from about the 11th May to the 
25th May. Between the 29th April and the 5th May, there is an evident 
overlap of the two emergence periods, and it is impossible to assign 
with certainty moths caught at this period to either generation. Plate 
VII shows the curve of emergence of both generations constructed 
geometrically from the curve of progressive daily totals, which may be 
considered to represent, with fair accuracy, the normal emergence 
curve of the species in the locality of Dehra Dun. It must, however, be 
remembered that the numbers of the second generation as compared 
with those of the first generation are relatively much reduced, owing 
to the local destruction of a large percentage of the first brood indivi¬ 
duals as a result of sack-banding. The two curves represent, therefore, 
not the comparative incidence, but the comparative periodic occur¬ 
rence of the two broods. 
Connection between the lst-2nd and 3rd-5th Generations. 
In order to determine if, and to what extent, saplings and young 
non-flowering trees are attacked by the 1st and 2nd generations two 
observation areas were selected in 1916. On the 4th February, 99 trees 
in Locality 1 and 164 trees in Locality 2 were examined, and all infested 
shoots pruned and destroyed. The percentage of attack (by the 5th 
generation) in the first locality was 68, and in the second 93. 
During the period of the flower and fruit broods, the trees were 
examined at intervals to discover, if any of the shoots showed signs of 
attack ; all trees were found to be immune. On the 20th June, 
no attack was located in the first locality ; but a few shoots were found 
to be bored in the second locality, on the 20th July the borer had appeared 
in both localities.* Examination at later dates showed a higher degree 
of infestation in the second area, probably because the first locality 
was not far distant from the experimental area in which sack-bands 
had been put up. 
The converse of this was observed at the end of July, 1914, when 
opportunity occurred to examine the crown of several felled mature 
toon trees. No attack was found except in a few soft epicormic shoots ; 
the majority of twigs in the crown of old trees are too hard and the 
season’s growth too short to be suitable for the development of 3rd and 
later brood larvse. 
* In May, 1914, numerous shoots of the current year were examined without finding 
larvae. On the 12th June, some 50 young toon were examined and found immune ; these 
trees were re-examined on the 20th June, 1914 and incipient attacks discovered. 
[ 189 ] 
