209 
useful, when it is deemed necessary to resort 
to them. 
There are but few of the Aphides tribe that 
are both ovipai-ous and viviparous, and still fewer 
that are altogether oviparous. Those which we 
find so prevalent on the Lai*ch, are, as far as I have 
been able to trace their different processes never 
viviparous. 
I make those remarks because any application 
for their destruction, while they are in the ova 
state, would avail nothing ; this is necessary to 
be understood, that the Horticulturist may save 
himself the trouble and expense of using the Re- 
cipes at an improper period. 
Those of the Aphides that are both vivipar- 
ous and oviparous in one year, will be found to 
establish the ova at the back end of the year, 
and the succeeding generations are produced vi- 
vipaiously. A circumstance of this kind will be 
found pretty clearly described in the account of 
one species infesting the Apple tree which may 
suffice without any further details. 
For the Destruction op Aphides,' — 
In most cases it will be proper to commence the 
destruction of the Aphides at their fii-st appearance 
on the plant, providing the plants will admit of it, 
that is, if there is no danger of disfiguring the 
plant, injuring the blossom, or destroying the 
young setting fruit. 
With respect to those which are on the 
Larch, and others which may breed in a similar 
