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those of the Phaloe'na niipta (Jîg. 278. ¿»), broAvn-
tailecl motil (c), currant moth (¿ ), common gooscb
en y moth (e), cabbage butterfly, ( / ) , spider (g),
house cricket (/¿), and cockchafer (/). Tlic eggs of
snails and slugs (a ) arc knoAvn from those of insects
by being much la rg er; they are of a bluish
white, Avith a considerable degree of transparency,
and are found in small clusters beneath the ground.
The period required for the hatching of eggs is
various; in some species this process takes place in
a fcAv days, Avhile Avitli others it is not accomphslicd
until the folloAving year.
1614. The larva, or caterpillar, is the first active
state of insects. The forms Avhich distinguish those of the different tribes are numerous
and varied ; but none are provided Avith Avings. They ai*e knoAvn in common language
by the names of grub, caterpillar, palmer-Avorm, maggot, and AvircAvorm. Tliese names,
if confined to particular tribes, may be retained with advantage ; thus, caterpillars sliould
be understood as applicable only to the laiwæ of Icpidopterous insects, as butterflies,
haAvk-moths, aud moths, and certain hymenopterous insects liaAung similarly formed
larvæ. Palracr-Avorms are usually hairy caterpillai’s of the moth tribe, and therefore this
name may bo disused. Grubs are the lai-A^æ of beetles; they are generally thick, fat, and
misshapen; often of a Avliitish hue (from their living in other bodies), and each is provided
Avith a distinct head, strong jaAvs, and generally with tlii’ec pairs of feet. Tlie grub
of the cockchafer (fig. 280. b) and of the insect called the Avircworm {fig. 281. a) are good
examples of these larvæ.* Maggots are soft, and seraitranspiu-cnt ; generally producing
flics (iUùscæ), or other tAvo-Avingcd insects (Díptera) ; they move along b y th e action of
the body on the ground, having no mdiments of feet : their heads are very small ; and
many species, such as the maggots found in putrid animal substances, cheese, &c., live
by suction. The lai*væ of bees, ants, &c. arc also popularly called maggots. The name
of AvircAvorm has been improperly applied to the larvæ {fig. 281. 6) of the crane flies,
Tipùlidæ {fig. 292. a, c), of Avhich there are numerous species ; they resemble maggots,
but are much more slender, and generally reside among the roots of gvass and aquatic
vegetables ; in the pupa state {figs. 219. f , and 281. c), they have the general form of tliose
of lepidopterous insects. The lai-A'oe of some tribes, as the locust and the grasshopper, differ
very little from the perfect insect, except in being destitute of Avings, the rudiments of
which only arc discernible ; Avhüe the spider, aud many other Avinglcss insects, emerge
from tho egg in their perfect form. A s examples of the most usual appearance of larvæ,
we may cite the grubs of the cockchafer {fig. 280. b), and of the nut beetle (c, d), and of
the bacon beetle ( / ) , in the same figure ; the caterpülai- of the cabbage {fig. 286. a ) aud
of the turnip butterflies {d) ; the maggots of the common flesh-fly (Jig. 293. c, d), of the
cheese fly or hopper (A), and of the bot and gadflies {fig. 291. c, é).
1615. In their larvæ state all insects feed voi-aciously, and ai'e, consequently, at this
period of their lives, the most destmctiAx to vegetables: yet they do not attack all plants
indiscriminately ; many, indeed, confine themselves to one pai-ticular species, without
which they die; others wiU eat the leaves of two or thi-ce plants only; Avhile some few are
general feeders. Hence it is that the larvæ of insects found in floAver-gardens are
generally different from those of the fields, and even from such as infest kitchen-gardens;
whilst orchards, again, are subject to a different race. The smaller species arc generally
the most injuiious, as they make use of many curious devices to escape observation : some
penetrate the heai-t of the young shoot, or eat thefr way into the bud ; many conceal
themselves with great skill, by roiling up the leaves in which they have taken up their
residence, and seeming the terminal openings by a slender Aveb j others, again, spin
themselves a sUken case, attaching to the outside small particles of dead leaves or other
substances, and thus live in security. These are more particularly the habits of Icpidopterous
insects^ all of which may be knoAvn by having two descriptions of feet ; those
toAvards the head being horny and jointed, while the rest are thick and soft, and are
called false feet.
1616. The pupa or chrysalis is the next state of insects. When the laiwa is full fed,
it retires either into the earth, or to some secure situation, Avhere its metamorphosis takes
place in-a feiv hours. The pupæ are as various in their forms and in thefr situations as
the larvæ. Those of the beetle tribes are found in tlie eai'th, or in other substances ;
they lia,VO usually the rudiments of feet, and of other parts which become fully developed
only in the perfect state. The pupæ of butterflies are entfrely naked ; and are either
suspended by the tail, or attached to trees. Avails, &c., by a strong transverse thread.
* The grubs of th e nut weevil, and of the other numerous species of th e tribe to which that beetle
belongs, are destitute of legs, and consequently come under the popular name of maggots. It is, m fact,
impossible to restrict such popular names as the above within systematical limits. (W.)
Moths, on the contraiy, pass this period of thefr existence either enveloped in a bag or
cocoon of tlieir OAvn spinning, or the clirysalis is found naked and buried in the ground.
The pupæ of flies and other two-winged insects are usually smooth, oval, aud affixed
externally or internally to those bodies which have given sustenance to the laiwæ.
The duration of the chrysalis state varies according to the species. There are some insects
Avhich undergo such a trifling chango that it is scarcely perceptible ; in general, however,
the pupæ ai'e torpid, inactive, and incapable
either of receiving nom-ishmcnt or ^ 279
of moving about. As examples of the
most common forms, we give those of the
cockchafer, (fig. 219. d), the turnip butterfly
(Ô), the peacock buttei-fly (c), the
currant moth (d), the gooseberry moth
(e), the crane-fly (Típ u la cornicina, / ) ,
Pln-ygaiiea rhombica {g), J fú sc a punii-
lionis, natural size and magnified (A A).
1617. The imago, or winged form, is
the last stage. An insect arrives at maturity,
in regard to coi-poreal bulk, in the
larva state, and never increases in size
after it emerges from the chrysalis; but it
is only in the imago state that all its organs
ai-e fully developed, and that it becomes
a perfect being, exliibiting those
c h a r a c te r s Avhich p o in t o u t its s ta tio n in n a tu r e . T h e h a b its a n d e c o n om y o f p e r fe c t i n se
c ts , n o less th a n th c i r e x t e r n a l a p p e ax a n co , a r e , in m o s t ca se s, to ta lly d iffé re n t from th o s e
Avhich b e lo n g to t h e p re v io u s s ta g e s o f th e i r e x is te n c e . T h u s , th e c a te rp illa i-, fu rn is h e d
Avith s tro n g jaAvs fo r d e v o iu -in g fo lia g e , is c h a n g e d in to a buttei-fly o r m o th , Avithout a n y
o rg a n s a d a p t e d fo r m a s tic a tio n , a n d w h ic h liv e s o n ly b y s u c k in g th e n cc tai- o f floAvers.
1618. The duration o f die lives o f insects is extremely vai'iablc. The majority, in aU
probability, are annua l; emerging from the egg, and passing through their metamorphoses
within the year. Yet there are many facts to prove that certain families (particularly
among the beetles) are long-lived. The late Mi'. Marsham detected a foreign
coleopterous insect in a piece of wood, Avhich formed a desk that had been in a public
office for nearly tAventy years : in which case, the lai'va must have been imported iu the
wood, ancl, not being disturbed by the joiner, must have remained the greater part of
this time in the larva and pupa states before it ate its way out as a perfect beetle. The
greater proportion of moths pass the winter underground in the chrysalis state. Butterflies
are mostly annual ; although some fcAv survive the Avinter, and appeal- early in the
spring : in many species, hoth of butterflies and moths, there arc, however, tAvo broods
in a year. The transitory life of the ièphémcra, or day-fly, is proverbial ; the perfect
insect, indeed, of some species exists but for a few houi-s, and seems born only to
provide for the continuation of its species ; yet in the lai-Ara state it enjoys an aquatic life
of two or thi-ee years. Bees are known to live for tAvo or three years ; and the same may
be said of those spiders which take up thefr residence in cellars and other dark abodes.
1619. The sexes o f insects a r c c om m o n ly tw o ; b u t n e u te r s a r c to be fo u n d am o n g
th o s e h ym e n o p te ro u s in s e c ts Avhich liv e in l a r g e so c ie tie s, n am e ly th e b ee , ant, and w a sp .
1620. Insects arc the most numerous of those organised beings which move upon the
earth. The number of species known to inhabit Great Britain alone is more than
10,000, and probably some hundreds still remain undiscovered. By this calculation, it
appears that there arc more than six insects to one plant. “ Noav, though this proportion,
it is probable, does not hold universally ; yet if it be considered hoAv much more
prolific in species tropical regions ai-e to our chilly climate, it may perhaps be regarded
as not very wide of a fair medium. If, then, we reckon the phanerogamous vegetables
o fth e globe, in round numbers, at 100,000 species, the number of insects Avould amount
to 600,000. I f AVC say 400,000, we shall perhaps not be very Avidc cf the truth ; and it
is probable that more than tlu-ce fourths of this number remain undiscovered.” {Kirby
and Spence, Int. to E n t , vol. iv. p. 477.)*
1621. On the arrangement or classification o f insects. H a v in g g a in e d a g e n e r a l k n ow le
d g e o f th o s e fo rm s a n d a p p e a ra n c e s w liic h in s e c ts a s sum e b e fo re th e y re a c h th e i r p e r fe
c t s ta te , th e s tu d e n t s h o u ld n e x t m a k e h im s e lf a c q u a in te d w i th th c i r cla ss ific a tio n , a n d
fin a lly Avith th e n om e n c la tu r e o f su c h a s ai-e m o s t in te r e s tin g . T h e firs t m a y b e a c q u ire d
b y a n a t te n tiv e p e r u s a l o f th e fo llow in g c h a r a c te r s ; b u t to a s c e r ta in th e n am e o f a
sp e c ie s , o r to k n ow Avhether a n y p a r ti c u la r in s e c t h a s b e e n d e s c rib e d , re c o u rs e m u s t b e
h a d t o b o o k s o r to th o s e p e r s o n s Avho h a v e m a d e e n tom o lo g y th c i r p a i-tic u la r s tu d y .
* Theve are more than 7000 species of weevils already described belonging to the single Linnæan
genus Curcùlio.
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