1903.] E. P. Stebbing— Life-History 0/ Chermes abietis-picea? Steb. 231 



return to the alternative host plant. This is evidently the case with 

 the silver fir series, since eggs have been found on needles which only 

 opened from the bud in May, and therefore could not have been those of 

 the autumn or winter stem mothers of the previous season. These eggs 

 hatched out, and quite young larva? were found on the fully-developed 

 silver fir needles six weeks after the spring larva? had first appeared. 

 There also appear to be other forms of the Chermes, and their feeding 

 causes the silver fir needles of the year to become distorted and to curl 

 and twist up, the individual needles being stuck together by the copious 

 sticky excretions of the Aphida?. This is especially noticeable on young 

 plants, at times 70 °/ to 80 % of the terminal portions of the branches 

 being treated in this way. 



I will now proceed to consider these life-cycles separately, first deal- 

 ing with the stages on the Spruce, and subsequently with those upon the 

 silver fir. 



The Chermes on the Spruce. 



At the beginning of May, 1901, an examination of the Spruce at 

 elevations of between 8,000 and 9,500 ft. in Jaunsar Barwar, in the N.- 

 W. Himalayas showed small pinkish-white cone-shaped masses appear- 

 ing here and there on the side branches. At the base of these in the 

 axil between the branch and the cone (which was an unopened bud) 

 masses of elliptical reddish eggs were to be observed, the mass being 

 partially covered by the dried skin of the stem mother who died as 

 soon as she had laid them. I have not as yet definitely ascertained 

 whether these eggs were laid in the previous autumn or in the April of the 

 year in which they were found. If at the latter period the stem mother 

 evidently lays very early in the season, as snow was still lying in shady 

 spots that year at the beginning of May at elevations of 9,000 ft. In the 

 first week of the month a careful inspection showed young larva? emerg- 

 ing from these eggs, and on cutting a section vertically through the small 

 cone, young larva? were visible in numbers between the bases of the 

 young needles. Under the microscope these larva? were seen to be 

 minute red aphids furnished with a pair of antenna? consisting of 

 two large basal joints followed by a narrower longer one which is 

 surmounted by a hair. The beak was long and coiled, and three 

 pairs of short legs were present. These minute larva? were engaged 

 in feeding upon the juices of the young undeveloped needles of which the 

 pink gall consisted. Other patches of eggs examined wer6 seen to be in 

 a less advanced state, the bud above them having only just commenced 

 to increase in size. The irritation set up by the young larva? feeding at the 

 bases of the needles soon causes the bud to swell, but instead of opening 

 out into a short stiff brush of needles it develops into a gall or pseudo- 

 J. 11. 32 



