Part I] Lindsay and Hardow : Lac and Shellac 
*5 
periods in a single growing season of the host. The apparent 
explanation of this fact (though it has admittedly not been proved) is 
that in India most trees, if they have not two growing seasons in the 
% 
year, have at any rate two periods in the growing season when their 
vegetative activity is much greater than usual. These periods are 
in the hot weather preceding the rainy season, and again in the 
autumn immediately after the rains. Most trees produce long shoots 
at both these periods and the flowering time is frequently at one or 
other of them. With a view to further consideration and enquiry it 
is here suggested that the period of intense lac production im¬ 
mediately following the impregnation of the female lac insect coin¬ 
cides with or is in some way dependent on the corresponding period 
of vegetative activity of the host; and that the reason why the 
winter brood takes so long to mature, and why a comparatively small 
amount of lac is produced before March, is that the host is then 
inactive and its branches contain very little sap before that month. 
Should this theory be found correct it will provide a simple explana¬ 
tion of the fact that in the autumn brood the male undergoes his 
metamorphosis in about one month while in the spring brood he 
takes 3J months ; on the assumptions, firstly, that he is waiting for 
the period of vegetative activity on the part of the host so that the 
abundant supply of food required by the female during the first part 
of the period of gestation may be forthcoming, and secondly that 
lac production by the female is a measure of food absorption. 
The lac insect appears to be able to sustain life for a time at 
least on almost any tree or shrub on which 
it is placed, but it is only on a few that it 
can thrive well and reproduce itself. Very much smaller is the 
number of trees and shrubs on which the cultivation of lac is of real 
commercial importance. The following are the more important 
species :— 
The principal host-trees. 
