116 PHYSIOLOGY AND DISEASES OF VEGETABLES. 
“ lion,” to eat up these aphides that are so destructive to the 
hop plants. 
We are instructed by the writings of Mr. Curtis, for par- 
ticulars of which I must refer the reader to the c Farmer’s 
Herald,’ to the publication, now proceeding, of 6 Morton’s 
Cyclopaedia of Agriculture,’ by Blackie and Son, and would 
refer to the copious list of farmer’s pests, under the term 
“ Insects,” for further information on this interesting subject ; 
but I would now remark that there are few insects but what 
have other smaller ones, which prey on them, and of some 
varieties of the aphis insect ; they are nearly all cleared away 
by these parasitic attacks. 
I have now before me some bearded ears of wheat that 
were gathered two years ago, and had been attacked by the 
aphis granaria , the ears having been stunted in their growth, 
the ground being a poor sand, without sufficient pabulum to 
fill out the ears. These aphides had been punctured by the 
Ichneumonides fly ; many of them had crawled to the beards 
of the ear, and there became attached by their gummy 
character, and there they now are, their skins retaining the 
character of the head and abdomen of the insect, the parasitic 
larva being gone. 
The aid of a microscope is required to show this pheno- 
menon, and the shell-like character of what remains of the 
original insect ; in some instances I have seen the remains of 
legs and antennae, many of the shells are retained between 
the chaff of the grains. 
Linnaeus had described a great number of the aphides , and 
asserted that every plant supported its distinct species of 
these insects, and he named them after the plants on which 
they fed ; and it is my attention to do so in this essay, as of 
the one now about to be described more particularly, which 
feed on the hop plants exclusively : it is termed aphis humuli. 
Its description will be a type of the whole family. 
Mr. Curtis is inclined, after an extensive and careful ex- 
amination of these insects, to subscribe generally to the 
opinion of the Swedish naturalists, viz., that each plant has 
its separate aphis , and he has described four varieties that 
feed on the Brassica tribe of plants, one of which only exists 
on the flower-stalks. 
The aphis humuli . — This variety belongs to the hop plant 
alone, and is found to infect that plant from the early part of 
May to the end of August ; and this year I saw many alive 
in the picking time, — middle of September. 
It is seldom that they are continuous during the whole of 
