114 PHYSIOLOGY AND DISEASES OF TEGETABLES. 
attack. When this happens after the hops have begun to 
show fruiting branches, it is then likely to be complete 
destruction to the crop. 
Mr. Gilbert White, in his ‘ History of Selborne,’ describes 
a flight of these winged aphides as alighting on the plants of 
his neighbourhood so late as the 1st of August, in the year 
1787* He says, “They probably were taking a flight from 
the grounds of Kent and Sussex, to the hop plantations of 
Alton and Farnham.” 
Previous to the final exit of the aphides, when their attack 
on hop leaves is prodigious, their cast skins may be observed 
on the top surface of those leaves, where other ones hang 
over them; and it is also generally observed that, during the 
height of their attack, few or no winged insects are to be 
found, but that previous to their final exit, some few fledged 
ones may always be observed. By the aid of a microscope, 
the eggs and the first hatching of the apterous progeny may 
be distinctly observed. 
When the leaves are fully developed, the unwinged aphis 
may be seen in all the stages of growth, and also may be seen 
to issue from the posterior part of its parent in a viviparous 
manner. 
The wings do not denote the sexes ; for, in the early as 
well as the late periods of their development, the males, as 
well as the females, are furnished with w r ings ; but there is a 
doubt if any of the male animals assume the form of the 
apterous or un winged insect. 
The males, then, are all presumed to have come forth from 
eggs, w hilst the females assume both forms ; but it is the 
winged ones only that deposit eggs. 
It has been remarked by all writers on this subject, that 
the males are few compared to those of the female, and that 
they appear only at the first commencement of the season, 
and at the latter end, when having fulfilled the design of 
nature, produced their kind, and enjoyed the pleasures of 
existence, they pass away like unto all animal creation. The 
services of the male not being required during the period of 
viviparous issue of progeny. 
The above is a general view and description of the appear- 
ances of aphides, to a casual observer of them on the hop 
plants. It is now necessary that a more particular descrip- 
tion should be given of this insect, which differs in some 
slight degree from other aphides. 
It is this one variety only which attack hop plants ; and 
they, like all the tribe, as well as most insects, have their 
paricides or enemies that exist by their destruction. 
