E N T O M 
are either fmooth or hairy, ("oft to the touch, or hard like 
fhagre'en, beautifully adorned with a great variety of the 
moft lively tints ; on each fide of the body nine flemmata, 
or little oval holes, are placed, which are generally confi- 
dered as the organs of refpiration. Therfe are on each 
fide of the head of the caterpillar five or fix little black 
fpots, which are fuppofed to be its eyes. Thefe crea¬ 
tures vary in fize, front half an inch long to four and five 
inches. 
The caterpillar, whofe life is one continued fuccefiion 
of changes, often moults its fkin before it attains its full 
growth ; not one of them arrives at perfeftion, without 
having calf its Ikin twice or thrice. Thefe changes are 
the more remarkable, becaufe when the caterpillar 
moults, it is not limply the fkin that is changed ; for we 
find in the exit via, the fkull, the jaws, and all the exterior 
parts, both fcaly and membranaceous, which compofe its 
upper and under lip, its antennre, palpi, and even thofe 
crufraceous pieces within the head, which ferve as a fixed 
balls to a number of mufcles ; we further find in the exu- 
via, the fpiracula, the claws, and fheaths of the anterior 
limbs, and in general all that is vifible of the caterpillar. 
The new organs appear under the old ones as in a {heath, 
fo that the caterpillar effedts the changes by withdrawing 
itfelf from the old (kin, when it finds itfelf lodged in too 
narrow a cornpafs. But to produce this change, to pufh 
off the old covering, and bring forward the new, is a work 
of labour and time. Thofe caterpillars who live in fo- 
ciety, and have a kind of neft or habitation, retire there 
to change their Ikins, fixing the hooks of the feet, during 
the operation, firmly in the web of their nefi. Some of 
the folitary fpecies fpin at this time a (lender web, to 
which they affix themfelves. A day or two'before the 
moment approaches, the infeft ceafesto eat, and lofes its 
ufual aftivity; in proportion as the time of change ad¬ 
vances, the colour of the caterpillar becomes more opaque; 
the fkin hardens and withers, and is foon incapable of re¬ 
ceiving thofe juices by which it was heretofore nouriflied 
and fupported. The infeft may now be feen, at diftant 
intervals, to elevate its back, and ftretch itfelf to its ut- 
moft extent; fometimes to lift up the head, move it a 
little from fide to fide, and then let it reft again. By re¬ 
peated exertions, all the veffels which conveyed the nou- 
rifitment to the exterior fkin are difengaged, and ceafe to 
aft, and a flit is made on the back, generally beginning at 
the fecond or third ring; the new fkin may now be juft 
perceived, being diftinguilhed by the frelhnefs and bright- 
nefs of its colour; the caterpillar then preffes the body 
like a wedge into this flit, by which means it is foon 
opened from the firft down to the fourth ring; this ren¬ 
ders it large enough to afford the infeft a paffage, which 
it foon effefts in a very curious manner. The caterpillar 
generally fafts a whole day after each moulting, for it is 
neceffary that the parts ihould acquire a certain degree of 
confiftency, before it can aft; in its ufual manner ; many 
alfo perifti under the operation. The body having grown 
under the old Ikin, till the infeft was become too large 
for it, it always appears much larger after it has quitted 
the exuvia : now as the growth was gradual, and the 
parts foft, the Ikin preffed them together, fo that they lay 
in a fmall fpace; but .as foon as the (kin is caft off, they 
are as it were-liberated from their bounds, and diftend 
themfelves confiderably. Some caterpillars, in changing 
their (kin, from fmooth, become covered with fine hair ; 
■while others, that were covered with this fine hair, have 
the laft (kin fmooth. The filkworm, previous to its 
chryfalis or pupa (late, cafts its (kin four times ; the firft 
is caft on the tenth, eleventh, or twelfth, day, according 
to the nature of the feafon ; the fecond, in five or fix days 
after; the third in five or fix days more, and the fourth 
and laft in fix or feven days after the third. 
Entomologifts diftinguifh the different appearances of 
the infeft in its pupa ftate, as follows: It is called coarc- 
tata , when it is confined to a cafe of a globular form, 
without the fmalleft refemblancc to the ftrufture of the 
OLOGY, 83.3 
infeft; it contains, as in the diptera. It is called obtetia, 
when the infeft is inveloped in a cruftaceous covering, 
confiding of two parts, one of which furroun'is the head 
and thorax, the other the abdomen. It is termed incom¬ 
plete, when the pupa has perceptible wings and feet, but 
cannot move them, as in meft of the hymenoptera. Semi- 
complete, when the pupa can walk or run, having only the 
rudiments of wings ; as in the clafs hemiptera. I lie dif¬ 
ference between the pupa and the larva of this order, is 
very inconfiderable ; as they eat, walk, and aft, juft as 
they did in their primitive ftate. Complete are thoie which 
take their perfeft form at their birth, and do not pafs, 
like other infefts, through a variety of dates, though 
they often change their fkin ; as is the cafe with many of 
the aptera clafs. 
It is a general rule, that all winged infefts neceffarily 
pafs through the larva and pupa ftate, before they affume 
their perfeft form : there are alfo infefts which have no 
wings, and yet undergo fimilar transformations, as the bed 
bug, the flea, &c. Other infefts, which have no wings, 
and which always remain without them, never pafs through 
the pupa ftate, but are fubjeft to confiderable changes, as 
well with refpeft to the number as the figure of their 
parts; thus mites have four pair of feet, and two fmaller 
ones at the fore part of the body, near the head; yet 
fome of thefe are born with only three pair of feet, the 
fourth is not evolved till fome time after their birth. The 
figure of the monoculus quadricornis changes confiderably af¬ 
ter its birth, The jitlus is an infeft with a great number 
offeet; and yet thefe at their birth have only three pair, 
the reft putting not forth till fome time after. 
When the caterpillar has attained to its full growth, 
and the parts of the future moth or butterfly are fuffi- 
ciently formed beneath its fkin, it prepares for its change 
into the pupa ftate; it feeksfora proper place in which to 
perform the important bufinefs: the different methods 
employed by thefe little animals to fecure this ftate of 
reft, may be reduced to four: fome fpin follicles or cones, 
in which they inclofe themfelves ; others conceal them- 
felve in little cells, which they form under ground ; fome 
fufpend themfelves by a glutinous matter at their pofte- 
rior extremity ; while others are fufpended by a girdle 
that goes round their body. Preparatory to the change, 
the caterpillar empties itfelf of all tire excrementitious 
matter that is contained in the inteftines, voiding at the 
fame time the membrane which ferved as a lining to thefe 
and the ftomach. The inteftinal canal is compofed of 
two principal tubes, the one inferted into the other; the 
external tube is compadt and flefliy, the internal one is 
thin and tranfparent; it is the inner tube, which lines the 
ftomach and inteftines, that is voided with the excrement 
before the metamorphofis. It generally perfeveres in a 
ftate of reft for feveral days, which affords the external 
and internal organs that are under the (kin an opportunity 
of gradually unfolding themfelves. In proportion as the 
change into the pupa form approaches, the body is ob- 
ferved often to extend and contraft itfelf; the hinder 
part is that which is firft difengaged from the caterpillar 
(kin ; when this part of the body is free, the animal con¬ 
tracts and draws it up towards the head ; it then liberates 
itfelf in the fame manner from the two fucceeding rings, 
confequently the infeft is now lodged in the fore part of 
its caterpillar covering; the half which is abandoned re¬ 
mains flaccid and empty, while the fore part is fwoln and 
diftended. The animal, by ftrong efforts, ftill forcing it¬ 
felf againft the fore part of the (kin, burfts the fkull into 
three pieces, and forms a longitudinal opening in the three 
firft rings of the body ; through this it proceeds, drawing 
one part after the other, by alternately lengthening and 
fbortening, {welling and contrafting the body and diffe¬ 
rent rings; or elfe, by pufhing back the exuvia, finally 
gets rid of its reptile form. 
The caterpillar, thus dripped from its fkin, now be¬ 
comes the pupa, nymph, chryfalis, or aurelia, in which 
the parts of the future moth are inclofed; but are fo foft, 
that 
