Page:Popular Science Monthly Volume 90.djvu/840

 The Birth of a Butterfly

A miracle which you may watch free of charge

��ALL butterflies must pass through four stages: first the egg; second the caterpillar or larva; third the pupa or chrysalis, and fourth the perfect insect or imago. Some species require months to complete the process. Many pass the entire winter in the third, or chrysalis stage, wound up in cocoons or buried in the ground or under stones or loose bark.

But the monarch, or ordinary milkweed caterpillar, passes through all four stages in from three to four weeks and has no objection to being an object of attention during the whole time, so long as plenty of fresh-cut milkweed is provided. Without this it would soon die, for the milkweed leaf is the only food it will take. It spends its entire caterpillar existence on the milkweed plant on which it happened to be born, eating greedily day and night except for a few hours every second day when it stops to change its skin.

This molting or skin-changing process is necessary because the little creature grows so rapidly that the old skin becomes too tight, like the breeches of a rapidly-growing boy with a very large appetite. The change itself is quickly accomplished, although the caterpillar finds

����it necessary to remain perfectly motion- less for fully two hours before and after the process. The skin simply splits down the center of the back and the caterpillar crawls out fully clad in a new suit just like the old one, only more comfortable. This happens five times during its caterpillar stage of existence.

If you want to witness the miracle of the eater- pi liar's transformation, simply break off the stem of the milkweed plant on which you find the next caterpillar you happen upon, and place the end of the plant in cool water. Be sure and place a fresh stalk in the water bottle each day so that your guest will be well supplied with food, but let the caterpil- lar crawl to the fresh stalk unaided. Handling may injure it. It will not try to leave you so long as you provide plenty of milk- weed.

The indications of the end of this first 'stage of existence will be a restless crawling about on the plant. The caterpillar is looking for the safest place to stay during the next stage of its career. Doubtless the spot

��The monarch, or milk- weed caterpillar which completes its transfor- mation in three weeks

��At left: Thp caterpil- lar attaching itself to a leaf by means of a sticky, silky substance

��The pupa emerging from an outgrown skin. The old skin is split open and dropped off

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