Monarch Butterfly Caterpillar on Yellow Milkweed
This turns into a Butterfly
Monarch Poetry by Angelo52
- Monarch Butterfly Poem
The life cycle of the Monarch in the form of a short poem.
Why the Monarch Caterpillar?
Why am I writing about this caterpillar you ask? After all I’m not really a bug guy, an entomologist, heck I can just barely pronounce the name. However I do like to look around my home and see what new critters have decided to share what I consider my space. One of these critters (actually there were a few of them) was the caterpillar of the Monarch butterfly.
So what would I know about this crawler? Well I know that they like to eat my flowers. I found the pictured caterpillar and its relatives feeding on the flowers I have been trying to grow at the side of my home. Turns out the plant, which I planted because of its pretty yellow flowers is known as the Silky Gold Milkweed, an import from South America, which provides the perfect meal for both the adult monarch butterfly and its offspring caterpillars. The adults will dine on the nectar that is inside the flowers, and the crawlers will feast on the leaves and milkweed sap and anything their mouths can get into their bellies.
Munch, Munch, Munch!
Monarch Caterpillar – Yellow Milkweed Terror
Did you know that the very beautiful and relatively large Monarch, who can fly thousands of miles to its wintering grounds in Mexico and California, starts life as an itty bitty tiny dot of an egg? That’s right, the caterpillars shown here, which will eventually transform into a black and orange white dotted butterfly with a wingspan that is a good 3 inches across starts out from an egg slightly bigger than the size of a period.
The larvae that hatch are tiny. So tiny are they that you may need to use a magnifying glass (or a 24x optical camera) to see the little things. If you are lucky you might even get a glimpse of the little caterpillars getting rid of the evidence of their hatching by munching the eggshell as their first meal. They aren’t really eating the egg casing to hide their presence but instead to get the nutrients that are still incased in the shell.
They then become the terror of the milkweed plant. They consume as much as they can 24 hours a day. Whole leaves can disappear into the maws of the caterpillar. Partially eaten leaves and leaves with holes or cutouts are the norm. They may even travel out to the tips of the plants and munch on the flowers. Yep – the eating machines can be destructive terrors to the milkweed plant but it’s only temporary and the plant can survive the attack to continue its own development. Within a day or two the plant will be putting out the pretty and showy flowers that attracted me to it in the first place.
Eating Machine on Leaf
Monarch Larvae Live to Eat
These guys and gals have a limited time period, about 14 days, to go from barely visible to the big 2 to 3 inch long caterpillars they can grow into. In those 14 days the larvae turn into the terrors of the yellow milkweed or any other milkweed they happen to be on. They eat and eat growing quickly until they reach the right length and have the right girth to enter the next phase of their existence.
About the only time they stop eating is to move to the next leaf where they can start the feeding again or to escape predators. Oh, and during their growth spurt they also stop a few times to molt out of their old skins and into new ones. Monarch caterpillars wear their skeleton on the outside of the body so as they grow they also have to spend some energy and effort in getting the old skeleton off to allow for the expansion. Not being wasteful, and due to the nutrients involved, they will promptly eat their castoffs. Then they will return to munching on the milkweed and drinking up its sap.
Predation Thins the Caterpillar Numbers
Predators and parasites take their toll. One estimate is that 90% of all eggs laid never reach maturity. Like all animals the Monarch larvae are most susceptible to getting eaten or killed off when they are small and young, and before they store enough milkweed poison in their bodies to become a bad meal.
Of course, humans also contribute to their mortality rates. When we indiscriminately spray poison on flowers and other plants to get rid of unwanted guests such as aphids, one consequence is the destruction of the Monarch caterpillar. You can see this caterpillar happily munching away on my Silky Gold milkweed plant because I chose not to use bug spray on these plants, hoping that it would give it a chance to become a butterfly.
As the Monarch caterpillar eats and grows it becomes more and more of a threat to predators. The milkweed leaf and sap it eats and drinks contains chemicals, known as cardiac glycoside, which the caterpillar’s body can store. This chemical is poisonous to most animals causing the predator to become ill. Since the caterpillar doesn’t want to be bitten, it advertises that it is poisonous through sporting bright, highly visible colors. The Monarch larvae are colored in yellow, black and white bands.
They are still cautious even when almost fully grown and highly colored. They will continue to eat the milkweed leaves from underneath them so the leaves themselves shield the caterpillars from overhead observation. They can also produce a silk lifeline and use it to quickly drop from a leaf if threatened.
The milkweed poison not only shelters the larger, surviving larvae from predators. These chemicals are also present in the adult butterflies offering them protection from birds and other predators that may be looking to add a little Monarch to their lunch menu.
Handsome Caterpillar soon to be Butterfly
Surviving Monarch Caterpillars Pass on the Genes
After 14 days of munching themselves into rapid growth, the caterpillars are ready for the next phase. This is where they may leave the milkweed plant that has been their home for the last couple of weeks and start their search for a sheltered place to hang around from.
All the ones on my milkweed disappeared overnight. Were they killed off by some predator that could tolerate their poison or did they move to find that perfect place to hang from? I sure wish I knew. I looked at all my Silky Gold plants and did not find any evidence of the Monarch larvae still being in residence.
So I will assume the best and hope that the larvae traveled somewhere where they felt more protected from the local environment to start their next journey. Perhaps they crawled over to the ficus bushes and have hidden themselves deep inside the tangled mess that these bushes provide.
If so, they are hanging from twigs or branches and have started the journey to become the adult phase Monarch butterfly. With a bit of the silk they can produce they will anchor themselves to hang like a small bell. Their bodies will transform into a chrysalis. Inside this chrysalis the rest of the caterpillar will change. The metamorphosis takes about 10 days and the survivors of this phase will crack open the chrysalis to emerge as adult monarch butterflies.
They will fly away, feeding on flowers, perhaps even on the flowers from the plants that the caterpillars fed on not so long ago. They will mate with other survivors who have made it to the adult butterfly stage. Then they will start the process again.
More information on Monarchs
- Monarch (butterfly) - Wikipedia, the free encyclopedia
From caterpillar to butterfly - Wikipedia talks it all.
- Monarch Butterfly Site: Life Cycle, Migration, Pictures, News, More!
Your BEST Monarch Butterfly information resource. Pictures, migration, life cycle, conservation, and links to more Monarch Butterfly websites.
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A Grown Monarch Caterpillar Visits
A Previous Caterpillar Sips Nectar
One morning this beautiful Monarch butterfly approched the Silky Gold milkweed growing next to my home. It flittered around for a bit, going up and down the plants, checking them out. Finally it settled on this batch of flowers and allowed me to capture it on film (digital camera, so captured on pixels - film just sounds better).
It would lift off, flutter around a bit, then settle on another batch of flowers. You could see it sticking its feeding tube into the flowers. Sometimes it would fly down among the leaves and land briefly before heading back up to the flowers.
After about 20 minutes, it lifted up higher and flew off in the breeze.