Fast Facts About Monarch Butterflies

FAST FACT 1: Monarch Butterflies are Poisonous.

Female monarch butterflies particularly choose to lay their eggs on a specific host plant for monarch butterflies: milkweed. This plant contains a highly poisonous sap. However, monarch butterfly larvae eating the plant are unaffected by the toxin, consuming the toxin to make themselves poisonous. Monarch butterflies tend to warn predators about their poisonous state with their bright, flashy colors both as larvae and adult. So, never eat a monarch butterfly!

FAST FACT 2: Migrating Monarch Butterflies Can Live Up for About 2-6 Months (World Wildlife Fund).

While most butterfly lifespans range about a couple weeks, some monarch butterflies can live for many months. In order to be capable of migrating across most of the northern hemisphere, monarch butterflies need to be able to live for a long time According to the World Wildlife Fund, this allows monarch butterflies to live for 2-6 months! This is definitely many times longer than a typical butterfly's lifespan.

For instance, the fourth generation of monarch butterflies on this map from the National Park Service migrate southbound along the entire east coast of the United States.

FAST FACT 3: Monarch Butterflies Use the Magnetic Field of the Earth to Migrate.

How do monarch butterflies know where to migrate exactly to their resting places in Mexico? They use a cool tool that the Earth has provided them! Thanks to the spinning magnetic field of Earth, monarch butterflies harness the power of the Earth's magnetic field to guide them to their destination. Now that is a cool way to navigate - no satellites needed!

FAST FACT 4: Millions of Monarch Butterflies Cluster in Trees in Mexico Every Winter.

As you can probably tell from these background images, one monarch butterfly is not the only one who gets the whole tree to himself or herself. Rather, they have to share it with their millions of other cousins! All of these monarch butterflies serve to form clusters in trees to nourish and be protected by their tree refuges during the harsh winters.

FAST FACT 5: Monarch Butterflies Aren't Born as Butterflies.

monarch butterflies follow a unique cycle of development in animals: complete metamorphosis. They first start out as eggs laid on leaves. When they hatch out of their eggs, they are born as monarch butterfly larvae known as caterpillars. These caterpillars have a white, black, and yellow stripe pattern, signaling to predators that they are poisonous. After several periods of molting from eating their milkweed plants, monarch caterpillars dangle in the form of a "J" shape underneath a supporting structure. They then turn green - don't worry, they are not sick! They are simply turning their insides into mush, molting one last time. But instead of a caterpillar underneath, a green pupa known as a chrysalis forms. Hardening shortly after the molt, monarch butterflies then develop new organs and structures to form the adult monarch butterflies we commonly think of. They then hatch out of their chrysalises, drying their wet wings to form as beautiful butterfly adults. They then go on to mate and, if female, lay more eggs on other sources of milkweed, starting the cycle again.

FAST FACT 6: Monarch Butterflies Consume Varieties of Milkweed Plants.

The most unique source of plant for monarch butterflies is milkweed. They do not eat magnolias. They do not eat roses. They do not eat irises. They eat milkweed, including swamp milkweed and butterfly weed. This plant provides a significant adaptation for monarch butterflies, as the plant is poisonous. This allows for toxins to be absorbed by the monarch butterfly larvae, allowing monarch caterpillars to warn predators that they are poisonous to eat.

FAST FACT 7: Monarch Butterflies Weigh About 0.5g (World Wildlife Fund).

It is important to be gentle with adult monarch butterflies. Why? Because they only weigh about half a gram, says the World Wildlife Fund on monarch butterflies. This small weight of adult monarch butterflies, much like birds and other flying insects, helps a monarch butterfly be capable of physically flying off the ground, as it is more resistant from gravity pulling it to the ground with its lightweight body.

FAST FACT 8: The Amount of Eggs that a Monarch Butterfly Lays is Around 700 (Oberhauser).

Monarch butterflies, like most insects, are a type of species known as an R-selected species. These types of species tend to have low survival rates as newborns, but produce many, many offspring! Monarch butterflies definitely exemplify the latter part of this statement. In fact, Journey North states that one female monarch butterfly can lay up to almost 700 eggs! Although this may seen like monarch butterflies can easily replenish their populations by producing many young, many of these young die early from environmental conditions and predators, not reaching the reproductive age of adulthood.

FAST FACT 9: The First Meal of a Monarch is its Eggshell.

Here's something shocking: The first meal of a monarch caterpillar is not milkweed. It first has to eat its own eggshell! Unlike other organisms that are born from shelled eggs, such as birds and reptiles, monarch caterpillars actually eat their eggshells when they first hatch. Not only does this clean up the plant by removing the eggshell off its leaves, but this is also intended to provide a source of protein nourishment for the newborn larvae. Then, it goes off to chomp on some milkweed!

FAST FACT 10: Monarch Butterflies Have Major Gender Differences.

It is almost impossible to tell what gender a monarch caterpillar is by just looking at it. They both look the same! However, monarch butterflies are easy to differentiate. Male monarch butterflies are physically larger than female monarch butterflies. But that's not all! Male monarch butterflies also have two black patchy spots on each lower part of their lower wings. Female monarch butterflies do not have these patches. These patches could potentially serve to make males more attractive for females, increasing chances of mating.

So what would the gender of the monarch butterfly in the image on the left be? If you guessed that it was a male because you saw the black patches on the bottom of its wings, you are correct!