PART I.

THE LIFE CYCLE OF A BUTTERFLY.

As is the case with all other Lepidoptera, butterflies pass through three very distinct stages before they attain the perfect form. These stages are:--1. The egg (_ovum_, plural _ova_). 2. The caterpillar (_larva_, _larvæ_). 3. The chrysalis (_pupa_, _pupæ_). The perfect insect is called the _imago_ (plural _imagines_).

The Egg.

Butterfly eggs are of various forms, and whilst in some kinds the egg-shell (_chorion_) is elaborately ribbed or fluted, others are simply pitted or covered with a kind of network or reticulation; others, again, are almost or quite smooth. If the top of an egg, such as that of the Purple Emperor (Plate 28), is examined under a good lens a depression will be noted, and in this will be seen a neat and starlike kind of ornamentation. In the middle of this "rosette" are, present in all eggs, minute apertures known as micropyles (little doors), and it is through these that the spermatozoa of the male finds entry to the interior of the egg and fertilization is effected. The changes that occur in the egg after it is laid are of a very complex nature, and readers who may desire information on this subject are referred to Sharp's "Insects,"