The Larch Buy. 
183 
Now the first he believes to be confined to the spruce, not 
migrating at all, and being entirely without a sexual generation. 
In his experiments he found the winged forms frequently 
laying their yellow eggs on various other conifers, but only 
when laid on the spruce did they come to anything. The 
second form has a periodic sexual generation, once in two 
years, always occurring on the spruce, while the intermediate 
purely female generation may take place either on the spruce 
or the larch. 
The existence of any Chernies entirely independent of a 
sexual generation is, if true, a very interesting biological fact ; 
but assuming Cholodkovsky’s conclusions to be correct, it is 
manifestly of practical importance to determine to which of 
these forms, if either, our British “ spruce bug 11 belongs. 
Further research may show that we have more than one species 
in the spruce galls, but certainly the one ordinarily observed 
corresponds more closely with Cholodkovsky’s second and 
migrating form than with the first, which he believes to be 
entirely confined to the spruce. 
Now to turn to the larch. The most careful search has not 
resulted in the discovery of any male insects among the 
Chernies infesting that tree. Is the common “ larch bug ” the 
intermediate form of the migrating spruce Chernies (which 
Cliolodkovsky calls Ch. viridis ), or is it another species which 
can exist exclusively on larches, and can dispense with the 
presence of males ? That such a species exists Cliolodkovsky 
believes, for he has found in Esthland a large green bristly 
Chermes on larches, which he calls Ch. viridanus, living on 
the buds and not on the needles, and laying its dark-green 
eggs on larches only. This, however, is certainly not our 
English larch bug, which much more closely corresponds to 
the insect which the Russian zoologist describes as alternating 
between the larch and the spruce. Certainly none of the 
cases of larch bug disease which have come under my notice 
during the last year are inconsistent with the view that both 
trees are necessary for its life-cycle. In one instance it was 
alleged that there were no spruce trees at all in a badly diseased 
larch plantation, but further inquiry elicited the fact that there 
were several not many yards away, and when branches from 
them were obtained for examination they were found to be 
dotted all over with the “ false cones ” characteristic of the 
disease on the spruce. There are two matters on which further 
light is urgently required. The first is a question for experts, 
and concerns the particular species of Chermes in each case of 
so-called larch bug or spruce bug attack. The second, which 
involves no expert knowledge at all, is the question whether 
there are any cases of larch bug disease in this country in which 
