92 
BEITISH APHIDES* 
under ground, where it attacks and oviposits on the 
young fibriles of the vine roots. These roots soon 
dilate into knots and knobs, and shortly after they 
undergo such a complete degeneration that the vine 
dies. In this manner entire vinevards have been 
destroyed and capitalists utterly ruined. [ . 
Future observation may show that other species of 
Aphis are dimorphous. Should this prove true it will 
much lessen the difficulty of accounting for the entire 
disappearance, during several months of the year, of 
many forms which are now known to feed exclusively 
on those annuals and plants which die off in early 
summer. At present we cannot prove the general 
fact of a migration coupled with dimorphism. 
A few remarks may be added upon the geographical 
distribution of Ajphides, notwithstanding that our 
present information unfortunately in this direction is 
but slight, inasmuch as the family has had but scant 
attention paid to it, except in the more civilized 
portions of the world. 
As far as we now know, the group is confined to 
the temperate regions of the globe, but over these 
regions species are widely spread. Some genera 
extend far north into cold and inhospitable regions. 
Thus in the extreme north of Chinese Tartary the 
Lachninae are represented by Lachnus picea ; this insect 
is also common to the north of Europe, and likewise 
may be taken on the pines bordering on the glaciers 
and snow of Switzerland. From the above district of 
the Amur, Mr. Walker has identified an Aphis, a 
native of Croatia, Dryohius Croaticus^ which he thinks 
(allowance being made for the obscure but undoubted 
modifications of colour arising from locality) very pro- 
bably is Dryohius rohoris of our woods. The same author 
also has described Aphides collected from China. 
Aphides are scattered far and wide over the whole 
continent of Europe, many species being common in 
Norway and Sweden, and extending more numerously 
through France, Germany, and Italy to Sicily. 
