pa enean aoe 
208 
bug alludes to the fact that the aphis causes 
many of the most destructive varieties of the 
mischiefs and desolations of plants which have 
long been popularly termed blights. 
The aphides are vastly more multitudinous, 
and far more generally and minutely diffused 
than any other tribe of insects; they inflict 
enormous damage upon the hop-grower, entail 
many serious evils upon the general farmer, are 
principal pests and tormentors of the gardener, 
and perpetrate devastations in temperate lati- 
tudes, which correspond in some degree to the 
devastations perpetrated by locusts in warmer 
countries; and yet they are individually minute 
and insignificant,—they are rarely so large as a 
medium-sized louse, and often appear to the naked 
eye mere moving points,—they form fine subjects 
of microscopic observation, and disclose gorgeous 
tints, wonderful organisms, and an astonishing 
economy to the pocket magnifier, —and they 
constitute the microscopic world of animated be- 
ing, the crowded communities of the leaves of 
the forest and the grasses of the field, the para-. 
disaical inhabitants of the perfumed and honeyed 
interior of flowers, the wonderful counterparts 
on plants of animalcules in water, of which popu- 
lar natural history has written so many glowing 
descriptions, and the fancy of many thousands of 
young learners have formed such vivid and ex- 
aggerated conceptions. The aphides inhabit 
every kind of plant, from the smallest grass to 
the most stately tree; and sometimes exist in 
myriads upon a single herb, of only two or three 
feet in height. Their species were supposed by 
naturalists of the last century to correspond in 
number and adaptation to all existing genera of 
plants; and, though only about seventy have 
been accurately observed and scientifically de- 
scribed, they possibly—if varieties or minor spe- 
cific differences be included—do not fall short of 
twelve or thirteen hundred. Some of the species in- 
habit several or even numerous genera of plants ; 
and other species are separated from one another 
in distribution among mere varieties of one spe- 
cies of plant; but by far the greater number 
occur in strict appropriation of a distinct species 
of the insect to one precise and exclusive genus 
or species of plant,—each variety of the insect 
having its own distinct plant, and receiving from 
it the specific name by which it is known in 
science. 
The feet or tarsi of all the aphides are two- 
jointed, the first joint very short, and the last 
vesiculous; the mouth has the form of a sucker 
or haustellum; and the ears or antenne have 
six or seven joints. The body of the larger divi- 
sion—or of the aphides proper as distinguished 
from the eriosomee—is soft and oval; the head is 
small and placed crosswise ; the eyes are entire 
and semiglobular ; the ears or antenne are larger 
than the body, often bristle or thread shaped, 
sometimes thickened towards the tip, and com- 
prising seven joints, the two at the base very | 
APHIS. 
short, and the next very long and cylindrical ; 
the sucker or haustellum has three distinct joints, 
and rises from the under part of the head between 
the forelegs, nearly perpendicular to the body ; 
the wings, when evolved, are four in number, the 
upper pair or elytrella longer than the under pair, 
and somewhat triangular; the legs are very long 
and slender, and occasion the gait of the insect 
to be awkward ; and the rump on each side above 
the vent has two hollow, immoveable, horn-like 
members, which serve to discharge the curious 
sweet liquid popularly called the honey dew. 
Fifty-seven species of this great division have 
been scientifically described ; and 21 of these have 
the ears or antennze long and tapering like a 
bristle, ten have the ears not tapering but thread- 
like, and twenty-six possess neither of these char- 
acteristics, yet have not been observed to exhibit 
any features which might constitute marks for 
classified subdivision. The body of the eriosoma 
or blight-bug division is usually covered with a 
light silky or cottony down; the abdomen has 
neither rump-horns nor tubercles ; and the ears 
or antennze are short and thread-shaped. We 
need hardly remark that these generic characters 
of aphis, as well as the subordinate characters 
which mark the various species, are ascertain- 
able only by microscopic observation. 
Almost all the well ascertained species possess 
interest, either direct or indirect, for the farmer 
and the gardener ; and—in spite of both the 
tediousness and the dryness of the detail—they 
require, or at least well deserve, to be severally 
indicated.—The oat plant-louse, Aphis avene, has 
a prevailing greenness of colour ; the members of 
its rump and the joints of its legs are black ; its 
head and the first joint of its ears are yellow ; its 
eyes are black; its legs are livid; and its tail’ 
has a bristle. This species is found in the ears 
of oats, barley, wheat, and rye; and it is supposed 
by some writers to be the cause of the remark- 
able excrescence called ergot or spur. See Er- 
gor.—The cabbage plant-louse, Aphzs brassice, is 
one-twelfth of an inch in length; and its general 
colour, when unwinged, is pale slaty gray, with 
a white mealy down over the body, and, when 
winged, dark green, with the head, eyes, and 
wing-ribs black. This species is found on cab- 
bage, turnips, broccoli, cauliflower, mustard, and 
similar plants ; and commences its ravages about 
the end of May or beginning of June, and con- 
tinues them till checked by the frost. It made 
fearful ravages upon cauliflower in 1826, upon 
cabbages in 1833, and upon turnips in 1827 and 
1836 ; and it may usually be seen in myriads un- 
der cabbage-leaves in July, and hid in the leaves 
of the crumpled broccoli so late as the end of 
November. Yet the Aphis brassice as a species 
must be understood as including several varie- 
ties. The male of it greatly magnified, is repre- 
sented in Plate XVJ. Fig. 1; the natural dimen- 
sions of the male in /%g. 2; the female in /%g. 3; 
and its natural size in /%g. 4. The cheapest 
