The Life-History and Anatomy of Butterflies 
Fig. 9 . — Upper end of 
egg of Pieris oleracea, 
greatly magnified, show¬ 
ing the micropyle. 
Fig. 10. — Egg? 
oiGrapta coni' 
ma, laid in 
string-like clus¬ 
ters on the 
under side of 
leaf. (Magni¬ 
fied.) 
pillar, after it is hatched, is destined to live, and the female re¬ 
veals wonderful instinct in selecting plants which are 
appropriate to the develop¬ 
ment of the larva. As a 
rule, the larvae are restricted in 
the range of their food-plants to 
certain genera, or families of 
plants. 
The eggs are deposited 
sometimes singly, sometimes 
in small clusters, sometimes 
in a mass. Fertile eggs, a few 
days after they have been deposited, frequently undergo a change 
of color, and it is often possible with a magnifying-glass to see 
through the thin shell the form of the minute caterpillar which is 
being developed within the egg. Unfruitfuleggsgen- 
erally shrivel and dry up after the lapse of a short time. 
The period of time requisite for the development 
of the embryo in the egg varies. Many butterflies 
are single-brooded; others produce two orthree gen¬ 
erations during the summer in temperate climates, 
and even more generations in subtropical or tropical 
climates. In such cases an interval of only a few 
days, or weeks at the most, separates the time when 
the egg was deposited and the time when the larva 
is hatched. When the period of hatching, or emer¬ 
gence, has arrived, the little caterpillar cuts its way 
forth from the egg through an opening made either 
atthe side or on the top. Many species haveeggs whichappearto be 
provided with a lid, a portion of the shell being separated from the re¬ 
mainder by a thin section, which, when the caterpillar has reached the 
full limit allowed by the egg, breaks under the pressure of the enlar¬ 
ging embryo within, one portion of the egg flying off, the remainder 
adhering to the leaf or twig upon which it has been deposited. 
Fig. 11 . — Eggs 
of Vanessa an- 
tiopa , laid in a 
mass on a twig. 
CATERPILLARS 
Structure, Form, Color, etc .—The second stage in which the 
insects we are studying exist is known as the larval stage. The 
insect is known as a larva, or a caterpillar. In 
5 
general cater- 
