

22 THE INSECT WORLD. 
nearly always called a worm, or grub, and in certain cases, a cater- 
pillar. 
Linnzeus was the first to use the term “larva”—taken from 
the Latin word Jarva, “a mask’’—as he considered that, in this 
form, the insect was as it were masked. At a certain period it 
ceases to eat, retires to some hidden spot, and after changing its 
skin for the last time, enters the third stage of its existence, and 
becomes a chrysalis. In this state it resembles a mummy en- 
veloped in bandages, or a child in its swaddling clothes. It 1s 
generally incapable of either moving or nourishing itself. During 
this period of its life the insect eats voraciously, and often 
changes its skin. It continues so for days, weeks, months, and 
sometimes even for years. 
While the insect is thus apparently dead, a slow but certain 
change is going on in the interior of its body. A marvellous work, 
though not visible outside, is being effected, for the different 
organs of the insect are developing by degrees under the covering 
which surrounds them. When their formation is complete, the 
insect disengages itself from the narrow prison in which it was en- 
closed, and makes its appearance, provided with wings, and capable 
of propagating its kind ; in short, of enjoying all the faculties which 
nature has accorded to its species. It has thrown off the mask ; 
the larva and pupa have disappeared, and given place to the per- 
fect insect. 
To show the reader the four states through which the insect 
passes in succession, in Fig. 16 is represented the insect known 
as the Hydrophilus,* firstly, in the egg state; secondly, as the 
larva, or caterpillar; thirdly, in the pupa; and fourthly, as the 
perfect insect, or imago. The different degrees of transforma- 
tion and evolution which we have just described, are those which 
take place either completely or incompletely in all insects. Their 
metamorphoses are then at an end. There are certain insects, 
however, that show no difference in their various stages, except 
by absence of wings in the larva; and in these the chrysalis is 
only characterised by the growth of the wings, which, at first 
folded back and hidden under the skin, afterwards become free, but 
are not wholly developed till the last skin is cast. These insects 
* A kind of water-beetle.—Eb. 
