The majestic monarch’s magnificent life cycle

A few more weeks and the monarch butterflies that are overwintering in Mexico will start making their way north.

Once coming out of hibernation, a female monarch will find a male with which to reproduce. Around the Texas/Mexico border, the female monarch will find milkweed plants on which to lay her eggs. She can lay 300-500 eggs in two-five weeks of egg laying.

Photo of a monarch egg

Photo by Bfpage, via Wikimedia Commons

Egg

Monarch eggs are yellow in color and are shaped like a football. They have a flat bottom attached to the milkweed leaf, usually on the underside of the leaf for safety, and then small ridges that lead up to a point.

The eggs are very small, only 1.2 mm tall and less than 1 mm wide. One millimeter is about the same width as the tip of a sharpened pencil — that’s tiny!

Monarch caterpillars hatch from eggs after three-five days, depending on the temperature.

Photo of monarch caterpillar

Larva

The larval stage of a monarch is called a caterpillar. When the caterpillar first hatches, it is 2-6 mm long. As it grows, it molts — sheds its skin — and ends up to be 25-45 mm when it is full grown. The time between molts are called instars, and monarch caterpillars go through several different instars, because they grow 2,700 times larger between hatching from an egg before turning into a chrysalis.

During the larval stage, caterpillars eat nothing but milkweed leaves. As milkweed is the monarch host plant, it is the only plant that its caterpillars will eat.

(See what milkweeds to plant to help monarchs.)

Monarch caterpillars live about 10-14 days.

Pupa

The pupal stage of a butterfly is called a chrysalis, unlike a moth’s pupal stage which is called a cocoon.

Before pupating, the caterpillar will use its spinnerets to spin a silk web from which it will hang upside down. The key is to look for a caterpillar hanging in the shape of a J, that means it is going to go into its chrysalis.

In chrysalis, the adult butterfly will develop for approximately 10-14 days. At the end of this metamorphosis, the chrysalis will turn black and then clear, as you’re able to see the black and orange butterfly inside just before it hatches.

Photo of a monarch butterfly hanging from its chrysalis

Adult

The adult butterfly will hatch and then hang as its crumpled wings unfurl and dry. You can see the butterfly pumping fluid into its brand new wings.

Once fully dry, the butterfly will begin to fly. It will find a mate, reproduce and the process starts all over again!

Did you know?

It can take four-six generations of monarch to make their way all the way to the northern most breeding grounds in the Midwest or southern Canada before the final generation migrates back south to Mexico for the winter.

(Test your monarch knowledge with this fun quiz!)

So when you see monarchs this spring, they are not the same monarchs that flew south last year. They are that monarch’s great-great-grandchild at least!

(Read “How do monarchs find their way south?”)

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