Danaus plexippus life history
Monarch (Danaus plexippus) Life History

Egg, 9-17-09

9-19-09, beginning to eclose, 3:17 p.m.

3:18 p.m.

3:20 p.m.


9-21-09, on flower buds

9-22-09; this one becomes food for a spider


9-27-09; a recently shed skin between the two caterpillars

9-28-09, final instar

9-30-09, beginning to pupate

10-1-09, fresh chrysalis

10-8-09, pre-emergent chrysalis

10-8-09, adult has just emerged

10-8-09, fresh Monarch Butterfly

I found several eggs on a volunteer milkweed plant, Asclepias oenotheroides, which was growing in my garden. I began watching them and was fortunate to be present when one of the eggs eclosed. Since I understood Monarchs to be safe from predators, I decided to leave the caterpillars on the plant. A few days later, to my surprise, I found a spider attacking one of them. Protection from birds does not mean protection from all predators! On the other hand, the spider may not have liked the taste, because it did not consume the whole body.

When it was about time for the caterpillars to pupate, I collected two and took them to my classroom. All went well, and my students enjoyed watching them emerge and become beautiful butterflies.

The caterpillars matured quickly, taking 12 days to pupate after they eclosed; the adult emerged 7 days later.

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