112 
ANNUAL REPORT OF NEW YORK 
the fact that they have not the first correct idea upon the subject on which 
they are writing. 
The truth is, these three maladies, about one and another of which so 
much lias been said, are all one thing — differing merely as cause and effect. 
If there were no lice on hops there would be no honey dew and no black 
blight. I am aware the hop growers will be much surprised at this state¬ 
ment, and will scarcely credit it, they have been so accustomed to regard 
these things as distinct from and in no wise connected with each other — 
deeming the honey dew to be a fluid which has exuded from the leaves in 
consequence of some disease therein, and the black blight to be, as already 
stated, a kind of fungus growing from the leaves, whilst the plant lice, 
occurring only on the opposite or under side of the leaves, appear to bo 
wholly separated from these substances upon their upper surface. But I 
am perfectly assured of the correctness of what I say, and can produce 
specimens which will demonstrate that I am correct. I regret that this 
subject did not occur to my mind last summer, or I would have had such 
specimens for exhibition here at this time. Upon the first opportunity, I 
will procure and place in the Museum of our Society, specimen of leaves 
showing this honey dew upon them, and others showing the black blight; 
and by the side of these leaves I will place white paste-board cards having 
the same honey dew and the same black blight ,upon them — thus demon¬ 
strating that these substances do not exude and grow from the leaves unless 
they also exude and grow from the paste-board cards. 
I will now briefly explain how these two substances come upon the 
leaves. 
Each Aphis has two little horns projecting from the hind part of its back, 
which horns are termed the honey tubes. From these tubes the fluid called 
honey dew is ejected, in the form of minute drops, like particles of dew, 
which, falling upon the leaves beneath them, the upper surface of the leaves 
becomes coated over with this fluid, more or less copiously as the Aphides 
producing it are more or less numerous. And now, th.s deposit of honey 
dew being exposed to the action of the atmosphere and alternately moist¬ 
ened by the dews at night and dried by the sun by day, is gradually decom¬ 
posed, changing from a clear, shining, transparent fluid, to an opake, black 
substance resembling soot, and it is then the black blight. In this simple 
manner do we account for and explain these phenomena — these three impor¬ 
tant diseases of the hop, about which so much has been said and such eru¬ 
dition has been displayed by some of the writers in our newspapers. 
These same phenomena, called honey dew and black blight, are not pecu¬ 
liar to the hop, but occur on other kinds of vegetation when infested by 
plant-lice; and an abundance of authority will substantiate my statement 
that this honey dew is caused by these insects. But I find no allusion to 
the black blight in any author, and what I state of that is the result of my 
own observations. It is proper, therefore, that 1 here adduce some of the 
evidence which I have, upon this particular point. 
It is over twenty years ago that I first noticed this blackness as being 
occasioned by plant-lice. Among several willow trees by the side of a 
stream near my residence, there was one so thronged with the willow aphis 
that I went several times to that tree to contemplate the spectacle which 
