When you see a Monarch butterfly flitting past, have you ever paused to think about that insect's remarkable life? Not many insects have as interesting a journey as the Monarch butterfly. This summer we had the opportunity to witness the beginning of this insect's amazing life. I'd like to share it with you.
This story really began early in the summer when a lone milkweed plant began growing outside the Stackhouse Education Center. Having studied Monarch butterflies in the past, I knew that milkweed was a host plant for the adult to lay her eggs on. Why you may ask? Because the milkweed is poisonous to most animals except the Monarch. When the eggs hatch, the caterpillars eat the milkweed leaves and end up storing the toxins in their bodies making them unsuitable for other animals to eat. So we began to keep a look out for any Monarch butterflies laying eggs on the milkweed.
Many weeks went by before any Monarchs were spotted. We frequently checked for eggs, but there were so many aphids that it was hard to see any. Then one day we spotted something on one of the leaves...it was so tiny we needed a magnifying lens to see it. At last...a Monarch caterpillar! The closer we looked the more we saw – there were about 6 tiny caterpillars crawling around munching away on the milkweed leaves.
The caterpillar spent the next two weeks eating nothing but milkweed leaves. In that time, the caterpillar typically grows 3,000 times its original size at birth - that's a lot of eating! This posed a bit of a problem...we just had one lone milkweed plant with 10 caterpillars on it. As you can see, the caterpillars defoliated the plant within a few days. We ended up harvesting milkweed from the Daffodil Bowl to supplement the dwindling foliage on the existing milkweed plant.
Throughout the 2 weeks, the caterpillar shed its exoskeleton 5 times.
The time in between the shedding is known as an instar. In the photo below, you can see 5 caterpillars in different instar stages.
Twelve days after we discovered the first caterpillar it left the milkweed plant and began to crawl up to the top of the window frame. When we returned the next morning, the caterpillar was hanging upside down in the shape of the letter "J" - at this point, we knew it was ready to go into its chrysalis.
When the caterpillar shed its exoskeleton for the last time, the green chrysalis was underneath. If you look closely you can see part of the yellow, black and white exoskeleton inside.
It's inside the chrysalis where the transformation takes place – this little black, yellow and white caterpillar with a chewing mouth and no wings emerges orange and black, with beautiful wings and a proboscis to sip nectar. What happens inside the chrysalis over an 8 day period is truly incredible! Below is a photo of the chrysalis 3 days after it formed. Note the gold bar and spots along the top and bottom.
As time passes, the green will begin to fade and the color of the wings will begin to show through. Once the butterfly emerges, this story does not end though – the life of the butterfly is just as amazing as the caterpillar's. Stay tuned for Part II of this story...