APHIS. 
which were deposited on the last year’s 
shoot ; though when it happens that the 
insects make too early an appearance, the 
greater part suffer from the sharp weather 
that usually succeeds, by which means the 
rose-trees are some years in a manner 
freed from them. The same kind of ani- 
mal is then at one time of the year vivipa- 
rous, and at another oviparous. These 
aphides which withstand the severity of the 
weather, seldom come to their full growth 
before the month of April, at which time 
they usually begin to breed, after twice 
casting off their exnvia, or outward cover- 
ing. It appears that they are all females, 
which produce each of them a numerous 
progeny, and that without having inter- 
course with any male insect : they are vi- 
viparous, and, what is equally singular, they 
all come into the world backwards. When 
they first come from the parent, they are in- 
veloped in a thin membrane, having in this 
situation the appearance of an oval egg ; 
these egg-like appearances adhere by one 
extremity to the mother, while the young 
ones contained in them extend to the other, 
and by that means gradually draw the rup- 
tured membrane over the head and body to 
the hind feet. During this operation, and 
for some time after, the fore part of the 
head adheres, by means of something that 
is glutinous, to the vent of the parent. Be- 
ing thus suspended in the air, it soon frees 
itself from the membrane in which it was 
confined ; and after its limbs are a little 
strengthened, is set down on some tender 
shoots, and is left to provide for itself. In 
the spring months, there appear on the 
rose-trees but two generations of aphides, 
including those which proceed immediately 
from the last year’s eggs ; the warmth of 
the summer adds so much to their fertility, 
that no less than five generations succeed 
one another in the interval. One is pro- 
duced in May, which casts off its covering ; 
while the months of June and July each 
supply two more, which cast off their co- 
verings three or four times, according to 
the different warmth of the season. This 
frequent change of their outward coat is the 
more extraordinary, because it is repeated 
more often when the insects come the soon- 
est to their growth, which sometimes hap- 
pens in ten days, when they have had plen- 
ty of warmth and nourishment. Early in 
the month of June, some of the third gene- 
ration, which were produced about the mid- 
dle of May, after casting off the last cover- 
ing, discover four erect wings, much longer 
than their bodies ; and the same is observa- 
ble in all the succeeding generations which 
are produced during the summer months, 
but still without any diversity of sex: for 
some time before the aphides come to their 
full growth, it is easy to distinguish which 
will have wings, by a remarkable fullness of 
the breast, which in the others is hardly to 
be distinguished from the body. When the 
last covering is rejected, the wings which 
were before folded up in a very narrow 
compass, are gradually extended in a sur- 
prising manner, till their dimensions are at 
last very considerable. The increase of 
these insects in the summer-time is so very 
great, that by wounding and exhausting the 
tender shoots, they would frequently sup- 
press all vegetation, had they not many 
enemies to restrain them. Notwithstand- 
ing these insects have a numerous tribe of 
enemies, they are not without their friends, 
if those may be considered as such who are 
officious in their attendance for the good 
things they expect to reap thereby. The 
ant and bee are of this kind, collecting the 
honey in which the aphides abound, but 
with this difference, that the ants are con- 
stant visitors, the bee only when flowers are 
scarce; the ants will suck in the honey, 
while the aphides are in the act of discharg- 
ing it; the bees only collect it from the 
leaves on which it has fallen. In the au- 
tumn three more generations of aphides are 
produced, two of which generally make 
their appearance in the month of August, 
and the third before the middle of Septem- 
ber. The two first differ in no respect from 
those which are found in summer, but the 
third differs greatly from all the rest. 
Though all the aphides which have hitherto 
appeared were female, in this generation 
several male insects are found, but not 
by any means so numerous as the females. 
The females have, at first, the same ap- 
pearance as those of the former generations, 
but, in a few days, their colour changes 
from a green to a yellow, which is gradually 
converted into an orange before they come 
to their full growth ; they differ, also, in 
another respect, from those which occur 
in summer, for all these yellow females are 
without wings. The male insects are, how- 
ever, still more remarkable, their outward 
appearance readily distinguishing them from 
this and all other generations. When first 
produced they are not of a green colour like 
the rest, but of a reddish brown, and have 
afterwards a dark line along the back : 
they come to their full grow'th in about 
