Metamorphosis

I have celebrated late summer the last several years by searching any milkweed plant I see, hoping to find monarch butterfly eggs or larvae. The last couple of years the search has proved unproductive but this year’s efforts with coworkers yielded two large larvae. These provided another chance to observe the amazing phenomenon of metamorphosis.

The larva does little but eat until ready to pupate. At this point it will begin to wander but eventually will spin a small knot silk on a stem (or another suitable location) and hang with the head curved up. It attaches to the silk with curved hooks on its two hind prolegs. This is called the “J stage” and the larva remains in this stage for about 24 hours.


When the filaments on the head appear very limp it is time to start observing closely.. The skin of the larva starts splitting up the back and the larva gyrates rapidly, all the while remaining attached to the stem, and pushes the larval skin up to where the prolegs are attached to the silk.

At this point the chrysalis is very delicate and the skin must be discarded. In a split second the chrysalis pushes a black postlike cremaster into the knot of silk, twisting to embed the barbed hooks on the end into the silk filaments. It then pulls the hooked prolegs from the silk and flicks the skin away by more vigorous twisting and turning. In 2-4 hours the skin of the chrysalis will harden and it will hang like a green and gold jewel for about 10 days.


During the last day or so the colors of the butterfly’s wings are visible through the clear shell of the chrysalis.


When the butterfly emerges its wings are quite small.


Over the next hour the butterfly will pump fluid into the black veins on the wings and they will expand to full size.



I never tire of watching this miracle.