Majestic Migrating Monarchs

Casey Leppo   Muhlenberg College Class of 2015



Laying out in your backyard, soaking up some rays you see a butterfly fluttering through your garden.  The beautiful creature has vibrantly colored orange, white and black wings.  You don’t even consider that this magnificent butterfly might actually be an insect.  Many people think of insects as being the bugs that eat the plants in your garden or the pesky flies and mosquitoes that are a nuisance when you just want to sit outside and enjoy the warm weather.  Some even think that all insects are scary-looking.  Well they couldn’t be more wrong!

Kenneth Dwain Harrelson

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The butterfly flying through your garden on a warm, summer day is actually the Monarch butterfly which plays an important role in our ecosystem, and especially in your backyard garden.  This butterfly starts out its life as a caterpillar and then metamorphoses into its butterfly form.  In its adult form, the brightly colored orange, black, and white butterfly reproduces and aids in pollination.  These Monarch butterflies are also capable of mass migration, but changes in our global environment have led to a large population decline of these unique insects.  

The Monarch butterfly feeds on the nectar of fruit-bearing, flowering plants while simultaneously aiding the plants in pollination.  Compound eyes can help the butterflies to see all around them when looking for flowers, including up, down, backwards, and forwards, all at the same time.  Receptors on their antennae are also capable of sensing the sweet odor associated with nectar so they can better orient themselves when looking for food.  Upon choosing a flower, taste receptors on the feet of the butterfly will confirm that the flower contains nectar.  They then unroll their tongue-like proboscis to suck up the nectar.  While feeding, they will pick up pollen from the flower on their feet and other appendages.  When they move to another plant to feed, they will transfer pollen from the first plant to the second, and pollinate the new plant.  This allows for plants to reproduce which helps to maintain a stable and healthy ecosystem, providing food for organisms of all shapes and sizes, including humans!

This majestic butterfly did not always look this way, though.  They started their lives as tiny caterpillars.  Monarch larvae are born from eggs laid on milkweed plants specially chosen by the adult female.  The larvae proceed to feed on milkweed, a plant which contains toxins that are not harmful to the caterpillars.  They store the toxin in their bodies and retain it for the entirety of their life.  These toxins are poisonous to predators and the vivid coloring of the adult monarch warns predators of their toxicity.  As the caterpillar chows down on its tasty milkweed meal during the larval stage, it passes through 5 phases, becoming more fat and colorful with each phase.  Then it enters into its teenage years, which in insect terminology is called the pupa stage.  In this stage, it lazes around all day, much like human teenagers, in a silk casing called a chrysalis that it made for itself.  While in the chrysalis, the larval cells die and the adult cells grow and divide rapidly, changing the caterpillar into what we know as a butterfly.  Once this metamorphosis is complete, the monarch butterfly that we all know and love emerges!  These butterflies live for a couple more weeks during which they reproduce and lay eggs.  The male is easily distinguishable from the female because they have a black dot on their hind wings. 

Monarch butterflies are capable of migrating south during the winter months to avoid the freezing temperatures typical of the northern United States.  The butterflies that live East of the Rocky Mountains, just like the ones here in the Lehigh Valley, travel to the mountains of central Mexico to over-winter.  This journey can be up to 3,000 miles long and the butterflies can fly up to 25 miles per hour! ¡Olé!  The butterflies that make this migration will remain in Mexico for the winter months and then begin the journey back North in spring-time.  Thus, those butterflies born late in summer that make the migration may be capable of living up to 8 months!  On the migration back North, the monarchs lay eggs and their offspring continue the journey.  Even though there are several generations between the butterflies that made the migration South to Mexico, the offspring are always able to find their way back to the same region and sometimes they even return to the same tree of their ancestors!

  

In recent years, climate change, destruction of forests in Mexico, and loss of the milkweed in the U.S. has affected the migration habits of these fascinating insects.  The North American Monarch population has dropped by 90% over the past two decades!  This species, which is one of nature’s greatest spectacles, is in danger of becoming threatened and it needs your help!  How could I possibly help, you may ask?  The most pressing need, currently, is to restore milkweed in the U.S. where monarchs are common or along migratory paths.  So plant a milkweed plant in your garden today!  Not only will you be helping the monarch butterfly population but you will get to enjoy their company in your garden and you will reap the benefits of the butterflies as pollinators!     

This Post by  Casey Leppo is licensed under a Creative Commons Attribution 4.0 International License.