BUTTERFLIES AND MOTHS. 7 
kinds of weather before they show any changes previous to 
hatching. These changes consist in a darkening of the eggs; 
in some cases, where the shell is thin, we can observe the 
gradual formation of the enclosed embryo, as shown in the 
illustration. As soon as ready the young caterpillar eats 
its way through the shell, and sometimes the very first meal 
it enjoys in the open air is the very egg-shell that protected 
it before. 
Caterpillars, which are the second state in the existence 
of all butterflies and moths, vary in every conceivable man- 
ner, as may be seen by studying the illustrations in the text. 
Usually, however, they are cylindrical beings, composed of 
head and twelve rings or segments. The head (Fig. 11), is 
the most specialized part of the larva; it is usually horny, 
since the muscles moving the powerful chewing organs are 
fastened to it internally. The illustration shows that it is 
separated by a central line (a) into two equal parts. The 
a triangular clypeus, the small ocelli (b), 
the antenne (c), the upper lip or labium 
with the horny jaws or mandibulz (d), 
are also shown. The under lip or labium 
is not seen, but the four-jointed maxil- 
lary-palpi (e), andthe two-jointed Jabial 
palpi(f) areshown. At the end of the 
labium is located a very important or- 
Fig. 11.—Headofcater- gan, the spinning-tube, through which 
pillar; b, ocelli; c, anten- 
nz; d, mandibles;e,max- the substance flows that is used by the 
illary palpi; f, labial palpi. : 
Enlarged. 
caterpillars to make the protecting 
silken cocoons. The caterpillars differ very greatly from the 
adult insect by possessing a biting and notasucking mouth, 
hence they can become very destructive to agriculture, horti- 
culture and forestry by consuming plants which we intend 
to use ourselves. The first three segments of a caterpillar 
behind the head are the thoracic segments, and to them are 
fastened three pairs of jointed feet, which later transform 
into those found in the winged insect; the other segments 
