520 The Potato Disease. 
sects, many species of which multiply with astounding rapidity, 
producing many generations in a summer, and a single Aphis in 
five generations, being the " progenitor of 5,904,000,000 descend- 
ants," according to Reaumur. They are to be seen in great 
abundance on the leaves and stems of a multitude of plants both 
herbs and trees. They exist in three states, the larva, pupa, and 
winged state. Mr. Smee indeed believes that the A. vastator is 
also viviparous or brings forth its young alive, which is rather 
improbable. 
The A. vastator is about one-tenth of an inch long in its ma- 
turity, with a large heavy body, of a greenish or olive color, and 
brownish in its advanced state, having two long and seven-jointed 
antennae which are turned in its quiescent state from its head 
backwards along the body, and in its perfect state having two 
pairs of wings of which the forward pair have twice the length 
of the other, and furnished with two abdominal spines projecting 
backwards from near the extremity of the body; the beak or ros- 
trum, by which it feeds on plants, is about one-fourth as long as 
the body, of three parts like to tongue and jaws and finely fitted 
for piercing the leaves and drawing up the aliment. 
This Aphis vastator has been found in great numbers on the 
Potato the present summer, in Pittsfield, Mass., and carefully ex- 
amined under a small and large magnifier, and identified as the 
insect described by Mr. Smee. Its numbers and its ravages on 
the Potato, Cabbage, Pigweed, Hop, and other plants, correspond 
to the descriptions of Mr. Smee, for he mentions perhaps thirty 
plants on which it lives, and on some of which it produces efTects 
similar to those on the Potato. The male insect was not certainly 
recognized by Mr. Smee, and, if seen in Pittsfield, is destitute of 
the abdominal spines. Wind and rain have destroyed them here 
as in England; and here too, they are followed by the same ene- 
mies, which destroy such multitudes of them, the Lady-bird or 
Coccinella, and the Scacoa pyrasiri, as figured by Mr. Smee. 
The wings of A. vastator enable the insects to diffuse them- 
selves widely and rapidly. They have not been noticed in such 
clouds as described in England. The Potato disease is known 
this year in Berkshire county, but has not yet been ascertained 
to be much destructive. Some careful observers have noticed the 
decay of the leaves as connected with the prevalence of this 
Aphis, and the resuscitated energies of the plant on the disappear- 
ance of the Aphis vastator after storms of rain and wind. 
No remedy, proposed by Mr. Smee, is adequate to prevent the 
existence of the disease. The Aphis is so small, multiplies with 
such rapidity, is so protected by the position on the under side of 
a leaf, and carries on its work in a manner so noiseless and fatal, 
that its ravages must go on. 
