_Variety_, a term by which two insects of the same species are known,
though differing a little (not characteristically) in colour, size,
&c.[16]
{xxiii}I shall next proceed to explain and describe the different parts
composing insects, by dividing them into the Head, Thorax, Abdomen, and
Limbs.[17]
The HEAD (Fig. 1, 2, 3, _a_.) includes the ANTENNÆ, MOUTH, PALPI, EYES,
TONGUE, JAWS, and HORNS.
The _Antennæ_ are formed of various shapes, according to the different
genera, as may be observed in the figures, and seem instituted by nature
not only for guiding the animal in its passage, but likewise for other
purposes; being endued with an exquisite sense of feeling and perception.
Fig. 1. _d d_. Fig. 2. _c_. Fig. 3. _c c_.
The _Mouth_ is placed in the head, but sometimes close to the breast, as
in the spider tribe; sometimes terminating in a horny beak, as in Plate
32. Fig. 1. also in Plate 42. Fig. 3 and 7. In some it is furnished with
strong mandibles like pincers, as in Plate 32. Fig. 6. and Plate 37. Fig.
1, 2, 3, 4, 5, 6. In others it is so covered and guarded by the palpi,
particularly among the moths, that it is not to be seen.
The _Palpi_ are parts placed close to the mouth, and variously shaped; as
may be seen by comparing those of the Lepidopterous with those of the
Coleopterous, and other tribes; consisting of a greater or less number
according to the species or genus; in some being only two, in most of
them four, and in some six, (Cicindela, Carabus, Linn.) The use and
purpose of these parts we are ignorant of. Fig. 1. _c c_. Fig. 2. _b_.
Fig. 3. _b b_.
The _Eyes_ are generally immoveable, and suited differently; in some to
see only in the night, in others in the day; and differ in number
according to the genera and species, having in general two only, but in
some five,[18] in others eight, as the spiders. Fig. 1. _b b_. Fig. 3. _d
d_.
The _Tongue_ (elongated maxillæ) is sometimes curled up spirally like the
spring of a watch, as in butterflies and some moths, &c. in others it
(including the labium) is doubled under the head, as in bees and wasps;
but a great many species are destitute of this elongated part.
The THORAX is principally composed of the BACK, BREAST, and in some the
SCUTELLUM, in others the MESOSTERNUM and DILATED POSTERIOR COXÆ.
The _Back_, dorsum or upper part, answering to the back in some animals,
terminates in some species in a triangular manner, so as to represent the
scutellum, as in Plate 33. Fig. 5, 6, and 8. Tab. Ann. Fig. 1. _f_. Fig.
2. _e_.
The _Breast_, or sternum, is the under part of the thorax, and always
furnished with legs.
The _Scutellum_ is a small but hard part like a scale, frequently of a
triangular shape, placed behind the dorsum of the prothorax, and joining
to it. It is not developed in every genus, being chiefly perceived in the
Coleopterous, Hemipterous, and transparent-winged orders.
The _Mesosternum_ is united to the fore part of the breast, extending
beyond the middle legs towards the fore ones; and observable only in some
species of the Coleopterous order. By Linnæus and several other authors
it is called sternum.
{xxiv}The _Posterior Coxæ_ are only conspicuously enlarged in some
particular species (dung beetles). There are two of them placed on the
sides of the breast next to the abdomen, under the hinder thighs. In some
they are placed remote and distinct from it, in others they lie close;
being moveable in some, in others they are fixed. The use of these parts
we are ignorant of.[19]
The _Abdomen_ consists of a number of annuli or rings, and contains the
greatest part of the intestines and other viscera; being united to the
trunk, and formed with holes on the sides, through which the insect
breathes.
The LIMBS comprehend the TAIL, LEGS, and WINGS, with their cases.
The _Tail_ is placed at the extremity of the abdomen; and in some is
furnished with a sting, in others it is armed with a pair of forceps;
sometimes with a single bristle, sometimes with a double one; in some
with a pair of claws like a crab, in others like a fork.
The _Legs_ include the coxæ, trochanters, femora, tibiæ, and tarsi; the
latter consisting of two, sometimes of three, four, or five
articulations. In some the fore ones resemble a crab's claws. Some are
furnished with spines, others are smooth and plain. The hinder ones are
formed for running, leaping, or swimming.
The _Wings_, being always two or four, are either plain or folded, erect
or open, lying flat or inclining downwards, &c. In some they are dentated
or scolloped; and some are furnished with two projections like tails.
They are also membranaceous, reticulated, or transparent, and frequently
adorned with beautiful colours. In some they are curiously folded within
two crustaceous cases, that are either smooth or rough, striated,
furrowed, punctated, &c. in some these cases are soft and flexile, in
others hard like horn; the Hemipterous are partly soft and transparent,
as in Plate 49. Fig. 2. and partly opake and hard, as in Plate 42. Fig.
1. Plate 43. Fig. 2. and Plate 45. Fig. 5.
It is necessary to observe, that I have not been so prolix and explanatory
in the foregoing definitions as I should be, if I intended to arrange the
figures under their respective classes, or establish any system for doing
so; I have explained no more _terms_ or _parts_ than what are sufficient to
enable the reader (if he is not an adept) easily and clearly to understand
the descriptions. It is likewise necessary to mention, that I have given
English names to most of the parts, where I could do it with the necessary
propriety for serving this particular purpose; and where I could not
substitute an English word, that was apposite and significant, I have
preserved the Latin one, as used by Linnæus and others. Thus, for instance,
the term palpi I would have altered, if I could have found an English word
that conveyed the same idea; but not easily finding one, I have kept to the
original. I have not forgot the terms mustachios, whiskers, &c. which I
might have used in its stead; but as these parts in many insects bore no
analogy or resemblance thereto, it being in a great many of them like a
short jointed filament or thread, I rather chose to preserve the Latin one.
The same practice I have observed with the term antennæ. For though feelers
is the general explanation given to this word, I could not prevail with
myself to use it. The reason is, because these animals seem to have a power
{xxv}of applying these parts to purposes different from that of feeling. By
the antennæ they are capable of distinguishing and perceiving, as well as
feeling; and I am strongly inclined to believe, it is by them the males are
capable of discovering the females at a great distance. It is certain their
powers of perception are very obvious and remarkable, which, by close
observations, we may soon discover; and unless we allow them capable of
smelling without nostrils, I do not know what parts they exercise, or by
what means they so readily discover, not only their females but their
respective kinds of food, the places proper for depositing their eggs, &c.
The male moths appear to have this faculty of discovering their females in
a greater degree than most other insects; for there are but a very few, if
any, belonging to this genus, whose females pass the first night after they
quit the chrysalis without coupling with the males; owing to unconquerable
_desire_ in the latter, and the strong effluvia or scent emitted by the
former for attracting their mates. Every adept is fully acquainted that a
female moth, known by the name of the Egger (Phalæna Quercus of Linnæus),
taken into the fields the first day it is hatched, will most certainly
(though shut up in a box) allure all the males round the country that are
within the sphere of its attraction, and even from a great distance; who
will at first fly round the box with wonderful swiftness and eagerness, and
afterwards settling thereon will hunt and run about it with the greatest
impatience, endeavouring to get at the inclosed female; and all this from
the strongest desire of copulation; for the minute that action is performed
by a male, the attractive property of the other ceases. The powers of
perception and distinction, therefore, are very great; and what parts of
the insects, unless it be the antennæ, are employed in this search I am at
a loss to discover. However, at present, I presume it will not be necessary
to offer any further reasons for using this term, as the name substituted
is sufficient for it to be known by, it will fully answer the intended
purpose.
The names of the other parts are too intelligible to require any
explanation.
The plate annexed (being the last thing I shall speak of) requires but
little to be said in its favour. The use and advantage of it is too obvious
to dwell on. I have already mentioned, that engravings and delineations
claim the preference in the highest degree of verbal descriptions; and as
such, I presume, the reader will find this plate of the greatest service in
assisting him to understand the descriptive parts with clearness and ease.
I must only recommend it to him, if he is desirous of avoiding difficulty
and trouble, to make himself fully acquainted with the terms and names of
all the parts of insects, before he begins to read the descriptions.
[Illustration]
Explanation of Fig. I.
_a_ The head.
_b b_ The eyes.
_c c_ The palpi.
_d d_ The antennæ.
_e e_ The shoulders. The patagia, or tippets, are placed here.
_f_ The thorax. The part underneath and opposite to this is termed the
breast.
{xxvi}_g_ The abdomen, with the annuli or rings of which this part is
composed; very conspicuous in such of the Lepidoptera as are figured in
Plate 27, 28, and 29.
_A A_ The anterior wings.
_B B_ The posterior wings.
_h h_ The bases of the wings.
_i i_ The tips.
_k k k k_ The anterior margin.
_l l_ The posterior or internal margin.
_m m m m_ The external edges.
_n n_ The lower corners of the anterior wings.
_o o_ The upper corners of the posterior wings.
_p p_ The abdominal edges. In the butterfly tribe this part forms the
abdominal groove.
_q q_ The anal angle.
_r r_ The tails; whereof some species have four, as in Plate 1, 2, and
7.
_s s_ The eyes on the wings. From round spots resembling an eye.
_t_ A waved bar.
_u u_ An irregular indented bar.
The terms upper side and under side, mentioned in all the descriptions of
the farinaceous tribe, require no explanation.
Explanation of Fig. II.
_a_ The head.
_b_ The palpi.
_c_ The antennæ.
_d_ The eyes.
_e_ The dorsum of the prothorax, commonly called the thorax in beetles;
whereof the under part is the prosternum.
_f_ The lateral margin of the thorax.
_g_ The posterior margin of the thorax.
_h h_ The upper horn.
_i i_ The lower horn.
_k_ The scutellum.
_l l_ The wing cases, or elytra.
_m m_ The suture.
_n n_ The lateral margin of the wing cases.
_o_ The anus.
_p_ The fore thigh.
_q_ The middle thigh.
_r_ The hinder thigh.
_s s_ The fore tibiæ.
_t t_ The middle tibiæ.
_u u_ The hinder tibiæ.
_w w w w w w_ The tarsi.
_x x x x x x_ The articulation of the tarsi with the tibiæ.
_y y y_ The articulation of the tibiæ with the femora.
_z z z_ The hooks or claws, (ungues.)
Explanation of Fig. III.
_a_ The head.
_b b_ The palpi.
_c c_ The antennæ.
_d d_ The eyes.
_e_ The prosternum; whereof the upper part is the prothorax.
_f_ The mesosternum.
_g g_ The dilated posterior coxæ.
_h h h h_ The abdomen, with its annuli or rings.
_o_ The anus.
_p_ The fore thighs.
_q q_ The middle thighs.
_r r_ The hinder thighs.
_s s_ The fore tibiæ.
_t t_ The middle tibiæ.
_u u_ The hinder tibiæ.
_w w w w w w_ The tarsi.
_x x x x x x_ The articulation of the tarsi with the tibiæ.
_y y y y y y_ The articulation of the tibiæ with the femora, or thighs.
_z z_ The hooks or claws, (ungues.)
Fig. IV. is inserted only to shew the three little eyes, which are placed
in a triangular manner, and mentioned in some of the descriptions, viz.
Plate 43. Fig. 4, 5, 6, &c.
{1}ILLUSTRATIONS