34 
THE SUBSTITUTE. 
soft in proportion to the weakness 
of their mandibles ; but before long 
they separate, and each of them 
proceeds to take possession of a 
separate stem or portion of a stem. 
They enter by piercing a hole at 
the lowermost portion, which they 
immediately cork up with gnaw- 
ings ; then they rise by degrees in 
the tube as they consume the pith, 
and the excrement tends to fill the 
empty portion. Should the plant 
be one of the Graminece, and con- 
sequently should the progress of 
the larva he stopped by a knot, it 
tries at first to pierce it, and, when 
it finds that this is impracticable, 
it constructs a circular opening 
hardly of the same diameter as its 
body, by which it goes out without 
being at the trouble to close the 
opening: it then recommences its 
operations, either above the knot 
or in a neighbouring stem, and 
thus continues till it has attained 
its size. When on the point of 
changing to a pupa, which hap- 
pens in the stem itself, it again 
forms an opening, but this time it 
only removes the inner substance 
of the stem, and leaves intact the 
external pellicle. The hole is no 
longer of the same size, and in- 
stead of being rounded is de- 
cidedly oval and much larger. 
One can see the object of this dif- 
ference, because the perfect insect 
iu quitting the stem would require 
a larger space, and having no 
mandii)les ought only to find an 
obstacle proportioned to the efforts 
which it can make with its head. 
As to the foresight which governs 
these dispositions, it originates in 
that astonishing faeidty which we 
qualify rather contemptuously as 
instinct, and on whicii reflection 
calls forth inexhaustible admira- 
tion. After having made all these 
arrangements, the caterpillar has 
only to consider how to place 
itself most conveniently to under- 
go its transformation. It spins a 
diaphragm of silk and gnawing's 
beneath it, and a second, similar 
to it, above it. Sometimes it even 
forms a complete cocoon formed 
of silk and gnawings, wherein it 
changes to a pupa. This is always 
placed vertically, but the head is 
sometimes placed uppermosl,some- 
times downwards ; in the latter case 
the hole for the exit of the perfect 
insect is at the bottom. M, Ram- 
bur has noticed instances of pup® 
driven out of the stem by the 
action of vegetation, when they 
had undergone their change at the 
summit. When the Nonagrics 
arrive at the perfect state they lose 
all the peculiar interest which 
attaches to their early stages: 
they then fly, as all other Nochue, 
at dusk, among reeds in moist 
j)laces. The females, furnished 
with an abdomen especially long 
and large, remain nearly motion- 
less all their lives. The males, 
much smaller and generally more 
lively coloured, have a tuft of 
diverging hairs at the extremity 
of the abdomen. (Vol. 1., pp. 99, 
100 .) 
TitE Study of Entomology. 
If the dignity of a study were 
in proportion to the magnitude of 
the object studied. Entomology 
would be pro])erly regarded as ’a 
trifling pursuit. The conceit of 
youth may be excused when the 
little vaunts itself over the less, 
but w'c are at .a loss to conceive 
why a man devoted to one pursuit 
slnmld sneer at the api'lieation of 
equal powers of mind to subjects 
