367 
1916-17.] The Family Chermesidse. 
Between 1st and 10th September, in the Royal Botanic Garden, 
Edinburgh, and in another wood on the Drumshoreland area, adult gallicolae 
belonging to the genus Chermes s. str. were found on spruce needles. The 
colour of the eggs laid by them was bright green, markedly different both 
from that of the eggs laid by gallicolae of Group A on larch, and from that 
of the eggs laid by gallicolae of Group B on spruce. These gallicolae 
appeared to correspond to those in the Borner experiment (6) establishing 
the unity of the non-migrans and migrans branches of the gallicolae of 
Chermes abietis, L., C.B., and to those described by Cholodkovsky (27) as 
Chermes occidentalis in Switzerland. 
Generation III. Colonici. — In nineteen to twenty-two days dark- 
green larvae hatched from the eggs laid by the gallicolae migrantes on 
larch. These larvae crept from beneath the wings of their dead mother, 
and in one to two days migrated from the needle to the bark of the 
branch or trunk. Small cracks and irregularities of the bark were used 
for protection. Strongly lighted zones, such as tops of exposed trees and 
upper sides of branches, were avoided. The larvae inserted their suctorial 
apparatus, secreted short curly “ wool,” and hibernated. From 1st March 
onwards the first-stage larvae of the colonici woke up and began to feed. 
The time of awakening and moulting was very irregular, probably due 
to varying degrees of protection. By 1st April some colonici had moulted 
three times, become adult, and begun egg-laying. Egg-laying, however, 
was not general until the beginning of May. Fifteen to thirty green eggs 
were laid under the protection of copious “ wool ” secreted by the mother. 
The egg-laying continued about a month. The eggs hatched in twenty to 
twenty-two days. The first iarvae hatching from a clutch of egg s were of 
the progrediens type ; they migrated to the needles (see Generation IV). 
Those hatching later behaved in a different manner. Most of them settled 
down around their dead mother, secreted short curly wool, and thus passed 
the summer and winter. The majority of the sistens larvae did not hatch 
until the end of June. Fresh larch shoots were offered to some on hatching, 
and they quickly climbed on to the needles. These latter sistentes were 
constantly observed during summer ; they remained undeveloped, and all 
such larvae had died by mid- August. Numerous sistentes were observed in 
nature on shaded dwarf -shoot needles; they did not secrete wool nor feed, 
and all died off before the end of the summer. These observations seemed 
to indicate that there was still some impulse within these sistentes urging 
them to attempt to develop immediately. 
Generation I V. Sexupara. — The sexupara generation developed on 
the larch needles. The feeding of the larvae resulted in a decrease in the 
