I 
I 
84 BEITISH APHIDES. 
f, 
Kyber found that the rose Aphis might be kept in : 
its viviparous condition for four consecutive years if , 
its habitat were artificially warmed. During this period j 
of his experiments neither male nor oviparous female ' 
appeared. But, notwithstanding so great an authority, ' 
more recent facts compel us to the conclusion that 
temperature alone, as before stated, does not determine 
the occurrence of these sexes. The duration of life of 
the viviparous larvae, on the other hand, is much 
affected by climatic action. Individuals will live for a 
considerable time if cold supervenes and -checks the * 
rate of their fertility. The larva of the rose Aphis may 
continue for a month or longer on its own natural 
feeding-plant, but in confinement I have not preserved ■ 
them above fifteen days. Stationary habits also would 
seem to have some effect in prolonging life, since I have 
observed isolated specimens of Lachnus pinicola located : 
on the same twig of larch for two months, during 
which time no young ones were born. ’ i 
The spent larvge of Siphonopliora rosce and other i 
species become much pitted and shrivelled from the | 
collapse of their integuments, and at the same time | 
their form becomes elongated. The cornicles or | 
syphons increase much in size, and their curvature 
becomes more marked. The colour of the insect 
usually darkens, and the form sometimes is hardly t 
symmetrical, on account of the unequal distension of 
the sides. 
^HE PUPA. 
i 
There is little doubt that the appearance of the pupa 
is mainly caused by the necessities of the colony urging j 
upon them a search for fresh food in other places. 
The viviparous female then gives birth to young, which ; 
speedily show a sort of tumescence upon the thoracic 
regions, from which muscular fasciculi are developed. 
In conjunction with these thoracic lobes four wing- 
