110 Papers. [JULY, 



It is not too much to say that man himself would be exterminated off the 

 face of the earth if this particular order of insects were not kept in check 

 by their numerous predaceous and parasitic foes. But the genus is 

 especially remarkable, in common with the well-known Phylloxera which 

 commits such serious depredations in European vineyards, owing to the 

 fact that one generation of individuals assume different habits to the 

 one that has preceded them, and so set up the phenomenon known as 

 «* parallel series." It is well-known that in the case of the Phylloxera, 

 one generation lives in galls upon the leaves, whilst a succeeding one 

 lives underground upon the roots of the vine. There is a European form 

 of the Chermes here described, and its life-history has been the subject 

 of the most lively discussion amongst European scientists, the investi- 

 gations of such renowned observers as Blochmann, Dreyfus and Cholod- 

 kovsky standing out the most prominently. Perhaps the latter may be 

 said to have given us the most lucid explanation in his paper published 

 as recently as 1890. This European form, which is named Chermes 

 dbietis — laricis, lives upon the Spruce and larch. The writer discovered 

 the Chermes here dealt with in the N.- W. Himalayas. In this region 

 the larch does not exist, and its place is taken by the Silver fir which is 

 generally to be found associated with the Spruce. The life-history of the 

 insect upon these trees, which appears to differ in a few points from that of 

 its European confrere, may be briefly summarised as follows : — A wing- 

 less parthenogenetic female of the Chermes either deposits her eggs upon 

 Spruce twigs and branches in the autumn, or hibernates through the 

 winter upon the tree and lays her eggs in the April of the following year. 

 These eggs, which are numerous, hatch out at the beginning of May, and 

 the young larvae collect round the base of the young developing need- 

 les on the branches and by suction cause them to swell up at their 

 bases. The needles thus coalesce, enclosing the young larvae, into a gall 

 or pseudo-cone. This grows on until it has the appearance of a young, 

 green fir-cone. Inside it becomes partitioned off into a number of cells » 

 in each of which a number of young larvae live and grow to maturity. 

 In the middle of July they are ready to undergo their last moult. The 

 cone then opens by shrinkage at the edges of the little doors, with one 

 of which eaoh compartment is furnished, and the little fat purple larvae 

 crawl out on to the outside of the false cone. They at once shed 

 their last skin and become perfect winged insects, most gorgeously 

 coloured, though these colours fade within a few hours. These insects 

 now take on different habits; some of them remain on the Spruce and lay 

 eggs thereon out of which young are hatched, which probably grow in- 

 to the hibernating females, whose offspring next year produce the 

 galls upon the tree. But another portion migrate to the Silver fir (in 



