ENTOMOLOGY. 
bloodless animals, which modern disco- 
veries have shewn to be contrary to fact : 
some of them, as the cimex lectularius, 
have been frequently used with the micro- 
scope, to exhibit in a striking manner the 
circulation of the blood. In this insect, 
with a good glass, the vibrations and con- 
tractions of the arteries may be distinctly 
observed. 
Most insects are oviparous ; of course, 
the first state in which insects appear is 
that of an ovum or egg. This relates to 
the generality of insects, for there are some 
examples of viviparous insects, as in the ge- 
nera Aphis, Musca, &c. From the egg is 
hatched the insect in its second or cater- 
pillar state; this second state has been 
usually known by the name of eruca, but 
Linnaeus has changed it to that of Larva, 
which see ; considering it as a sort of mask- 
ed form or disguise of the insect in its com- 
plete state. The larvae of insects differ 
very much from each other, according to 
the several tribes to which they belong ; 
those of the butterfly and moth tribe (pha- 
laena) are generally known by the name of 
caterpillars; those of the beetle (scara- 
baeus), except such as inhabit the water, 
are of a thick, clumsy form. The larvae of 
the locust, or grasshopper, (gryllus), do not 
differ very much in appearance from the 
complete insect, except being without 
wings. The larva; of flies, bees, (musca, 
apis,) &c. are generally known by the 
name of maggots, and are of thick short 
form. Those of water beetles (dytiscus) 
are of highly singular forms, and differ, per- 
haps, more from that of the complete in- 
sect than any others, except those of the 
butterfly tribe. Some insects undergo no 
change of shape, but are hatched from the 
egg complete in all their parts, and they 
undergo no farther alteration than that of 
casting their skin from time to time, till they 
acquire the complete resemblance of the pa- 
rent animal. In the larvse state most in- 
sects are peculiarly voracious, as in many 
of the common caterpillars. In their per- 
fect state some insects, as butterflies, are 
satisfied with the lightest nutriment, while 
others devour animal and vegetable sub- 
stances with a considerable degree of 
avidity. When the larva; is about to change 
into the chrysalis or pupa state, it ceases to 
feed, and having placed itself in some quiet 
situation, lies still for several hours, and 
then, by a sort of effort, it divests itself of 
its external skin, and immediately appears 
iu the different form of a chrysalis or pupa ; 
in this state likewise, the insects of difc 
ferent genera differ almost as much as the 
larva. In most of the beetle tribe it is fur- 
nished with short legs, capable of some de- 
gree of motion, though very rarely exerted. 
In the butterfly tribe it is destitute of legs ; 
but in the locust tribe it differs very little 
from the perfect insect, except in not hav- 
ing the wings complete. In most of the 
fly tribe it is perfectly oval, without any 
apparent motion or distinction of parts. 
The pupa of the bee is not so shapeless as that 
of flies, exhibiting the faint appearance of 
limbs. Those of the dragon-fly (libellula) 
differ most widely from the appearance of 
the complete insect ; from the pupa emerges 
the insect in its ultimate form, from which 
it never changes, nor receives any farther 
increase of growth. 
Different naturalists have attempted to 
arrange insects into families and genera, par- 
ticularly the celebrated Linnaeus, whose ar- 
rangement may be thus explained. He has 
formed them into seven families or orders, 
composing his sixth class of animals, In- 
secta : he defines an insect, a small animal, 
breathing through pores on its sides, fur- 
nished with moveable antennae and many 
feet, covered with either a hard crust or a 
hairy skin. As introductory to the distin- 
guishing marks of the orders and genera, it 
will be necessary to enumerate and explain 
the terms given to the different parts, and 
the most remarkable of the epithets he has 
applied to them. The body is divided into 
head, trunk, abdomen, and extremities. 
I. Caput, the head, which is distinguish- 
able in most insects, is furnished with eyes, 
antennae, and most frequently with a mouth ; 
the eyes, two, four, six, or eight in number, 
destitute of eye-lids, are either small and 
simple; or large, compound, and hemi- 
spherical ; or polyedral ; they are commonly 
immoveable ; they are called stipitati, when 
placed on a stalk. The antenn® are two 
articulated moveable processes, placed on 
the head; they are eitherj 1 . Setacea, se- 
taceous, i. e. like a bristle, when they taper 
gradually from their base, or inserted into 
the head to their point. 2. Clavatae, cla- 
vated, i. e. club-shaped, when they grow 
gradually thicker from their base to their 
point. 3. Filiformes, filiform, i. e. thread- 
shaped, when they are of an equal thick- 
ness throughout the whole of their length. 
4. Moniliformes, moniliform, i. e. of the 
form of a necklace, when they are of an 
equal thickness throughout, but formed of 
a series of knobs, resembling a string of 
