THE FOURTH STAGE OR IMAGO
When the chrysalis stage is over the outer skin bursts open about the head, and the imago—the butterfly proper—crawls out. The newly emerged butterfly is a sorry-looking specimen; the wings are very small and flaccid, and it can do no more than cling to some convenient support, usually the empty skin of the chrysalis. After a while, however, the body juices flow out into the wings, which expand and harden, and in a few hours the young butterfly is flitting from flower to flower with its fellows.
Ordinarily the imago does not live long—often only a few days. Just as the caterpillar’s sole business is to eat, the mature butterfly has only one important function, and that is reproduction. It speedily finds a mate (that’s what its wings are for), contributes its quota of ova or sperm to produce another generation of caterpillars, and its ephemeral existence as a butterfly is over.
CHAPTER IV
THE CASE OF THE RED SILVERWING
Having dealt briefly with the transformations of butterflies in general, it may be well to examine more closely into those of a single representative species. For this purpose I have chosen Dione vanillae, known as the Red Silverwing, and have described each stage and transition in considerable detail. The following paragraphs are extracts from the daily records of a study I made in southern Kansas, the northern limit of vanillae’s usual range.