24 
Indian Forest Records . 
[Vol. VI 
Mandla Division, and suggests that the eggs were laid late in February 
or early in March. At the same time beetles were found boring into 
newly felled trees and engaged in ovipositing. 
Summary of the Seasonal History. 
From the data given above, although disconnected and extending 
over a period of three years, it is possible to arrive at fairly definite 
conclusions as to the life-cycle and seasonal history of Diapus furtivus. 
We have stated that the length of the life-cycle from egg to mature 
beetle approximates to a period of 10 or 11 weeks, but that this period 
does not necessarily represent the length of a generation, since the 
oviposition period of the female is variable and the feeding period of 
the young beetle before swarming is also variable. The variation from 
the average is influenced directly by the degree of freshness of the 
infested timber, resulting from rapid or delayed evaporation of sap. In 
the former case, the periods of attack and of emergence are shortened, and 
in the latter case, they are lengthened, while the periods of development 
conversely are respectively extended and decreased. 
Under the most favourable conditions, it would be possible for a 
theoretical series of five generations to occur, provided that freshly 
felled or dead timber is available at each of the successive swarming 
periods. Under normal conditions, however, it is unlikely that a 
complete series of generations is carried through in any one locality. 
Primarily the absence of suitable breeding material at the time of 
emergence of many of the broods results in failure to carry on to 
the next generation. The swarming beetles are forced to attack either 
living healthy trees, or dead and dry timber. In the'former case, they 
rarely penetrate further than the outer layers of the sap-wood, where 
they are drowned in a flow of resin which invades the entrance gallery ; 
in the latter case, the scantiness of sap is insufficient to provide nourish¬ 
ment for the complete development of the larvae, which dry up in the 
galleries and die with the parent beetles. The variation, which occurs 
in any one brood, in the length of the periods of egg-laying, larval develop¬ 
ment and feeding period of the young beetle, destroys all possibility 
of recognizing in the forest a regular succession of generations, swarms, 
attacks, etc. It can be said with accuracy that, on any day during 
the rains, cold weather and early hot weather, it is possible to find in a 
Sal forest all stages of Diapus furtivus from the egg to the flying beetle. 
In a particular spot, and especially in a particular tree, it is true that 
one stage in the life-cycle may predominate numerically over the other 
[ ^4 ] 
