CHERMES HIMALATENSIS OX THE SPRUCE AND SILVER FIR. 119 



this time having dried and shrunk apart to some extent, thus permitting the exit of 

 the larvae. These larvae or nymphs shed their last skin and emerge as winged insects. 



A portion of these winged individuals remain on the Silver Fir, develop a cottony 

 material, and oviposit on the needles or stem of the tree, the egg-masses heing covered hy 

 the cottony substance. The remainder of the winged generation migrate to the Spruce 

 and are to be found on the needles of that tree. These probably give rise to a sexual 

 generation (Sexuales) upon this tree. 



Thus by the end of June we have on the Silver Fir egg-masses covered by a cottony 

 material laid on the needles or on the bark of the stems of saplings and brandies of 

 older trees. The position is therefore much as it was at the end of April. 



These eggs hatch out within a week or so, giving rise to tiny blackish-brown insects 

 covered with white cottonv bristles and edged with a fringe of white setae, which crawl 



w O CI y 



onto the stems covered with a first young cortex and bury their long proboscides through 

 crevices into the cambium layer below (PL 23. figs. 2, 3). These larvae are a portion of 

 the Colonici and remain here through the rains and through the ensuing autumn and 

 winter, eventually laying the eggs of the spring generation. 



It would appear possible, however, that some of the Exsules may mature and lay 

 eggs in the early autumn towards the close of the monsoon about the beginning of 

 September, since I have found dead winged flies very commonly with their proboscides 

 fixed on the under side of the needles of Silver Fir at the end of September and 

 beginning of October. These flies could not be those which issue from the pseudo- 

 cones on the Spruce in the middle of July and migrate to the Silver Fir, for such 

 minute fragile things could never pass two months in such an exposed situation as the 

 under surface of a Silver Fir needle during the monsoon season without being blown or 

 washed off. 



I can only at present account for the presence of these winged individuals on the 

 Silver Fir at this period by the above supposition, unless the winged insects come from 

 some belated Spruce galls which did not open before the monsoon broke over the hills. 



IV. Table summarising the Life History on the 

 Spruce and Silver Fir. 



In the first section of this paper I have given the table from Burdon's paper showing 

 the development of the various generations of the European insect on the Spruce and 

 Larch in the two-year rotation. 



Under the individual trees I have given a summary of the generations of the insect 

 passed through on each. 



The following (p. 120) is a rough attempt to construct a table for the generations of the 

 Himalayan Insect similar to the one drawn up for the European species on the Spruce 

 and Larch. 



