74 
BRITISH APHIDES. 
of migration to be relied on, may be found in Aphis 
rumicis, which has its numerous synonyms from the 
names of the plants on which it feeds. It passes the 
autumn and sometimes lays its eggs on the furze, Ulex 
JEuropcBUs, and thus it affects this plant both before 
and after the growth of its more usual food — the broad 
bean. Notwithstanding these examples of migration, 
we have no certain knowledge of the winter habitats of 
numerous species which seem to occur only during a 
few weeks of midsummer, such as Siphonophora mille- 
folii^ which may be found from July to September, and 
then entirely eludes our notice for the rest of the 
year. 
We find much difference in the locomotive and 
active habits of this family. Some genera, like Galli- 
pterus, are almost solitary, and rarely move more than 
one or two inches from the leaf on which they have 
been dropped, whilst others — more like the Oicadidae 
— ^almost run, and try to conceal themselves from the 
observer by retiring to the opposite side of the twig. 
The walnut Aphis, Gallipterus juglandis^ affects the 
midrib of the under side of the leaf ; but the smaller 
species, (7. juglandicola, singularly feeds alone on the 
upper surface of the leaf. Aphis cardui, and others, 
encrust the ffower-stalks of the thistle and other 
plants, whilst another species covers with their hun- 
dreds the yellow spadix, within the spath of the Arum, 
Reference to the great bark-feeding Aphis, Lachnus 
quercus, has already been made. Ghermes corticalis 
similarly also draws its nourishment from the rind of 
the fir-tree. 
Finally, various modes of concealment are adopted 
by different kinds, amongst which may be instanced, 
as two of the most remarkable, the construction, by 
Ghermes abietis, of those conical, or pineapple-like 
receptacles, which curiously mimic the fruit of the 
spruce-fir, and the large pseudo-galls formed by 
Schizoneura on the poplar-tree. Less curious are the 
coloured blisters raised on the leaves of some plants 
