76 
BEITISH APHIDES. 
better position for stating this now that the true sexes 
of twelve or more species are known, and have been 
satisfactorily made out by dissection. 
THE OYUM. 
The egg-laying process happens at different seasons 
of the year according to the habits of different genera. 
The exclusively oviparous Ghermes laricis (Chermesinse) 
deposits her eggs continuously throughout the spring 
and summer months, after which she discontinues the 
process. The last brood — whether impregnated or not 
is yet uncertain — hybernates and survives the frosts of 
winter. It wakes to active life in the months of February 
or March. This hibernation of the foundress of a colony 
(the Altmiitter of Koch) is somewhat exceptional. In 
almost all other cases (Aphidinee) the oviparous female 
oviposits in late autumn and then dies. Usually the ap- 
pearance of the male precedes by a few days that of the 
oviparous female, and some short time elapses before 
the process of egg-laying commences. It has been sug- 
gested that the presence of the male acts as a stimulus 
to the winged female, which stimulus results in the 
birth of a perfect instead of an imperfect sex. Further 
researches, however, are required before the existence 
of such a cause can be asserted as an ascertained fact. 
The egg most commonly has the shape of a long 
oval, the major axis of which is often double the length 
of the minor axis. The ends are in general equally 
rounded. At the time of deposition the ova are com- 
monly yellow, or pale ochreous in tint, but after some 
hours’ exposure to the air they often turn to a fine 
shining black or deep brown. When first extruded 
they are lubricated by a glairy, tenacious fluid, which 
acts as a cement, by which the insect attaches them 
to twigs or the stipules which surround the young 
buds. 
The ova of Aphides are disposed very differently, 
