Milkweed to Monarchs

Every year, spring’s arrival transforms the local landscape.  We admire the newly filled-out trees of green and anticipate summer pleasures such as vacations, warm days at the pool, and visits to the shore. Some become the architects of gardens and add their own displays of brilliant color to complement native greenery and blooming plants through summer and fall.  As for me, I look forward to the sight of growing milkweed plants in meadows and by the roadside.  The appearance of milkweed tells me it will soon be time to search for my first monarch caterpillar egg of the season.  The milkweed, with its large and simply-shaped leaves, is a humble plant few would call beautiful unless seen in full bloom.  However, as host plant for monarch caterpillars, milkweed is essential to the life cycle of the iconic monarch butterfly.  If you can find milkweed, you can find monarch caterpillars and eggs.  The native milkweed species common in New Jersey is known as Swamp Milkweed, or Asclepias incarnata.  The surest way to identify this plant is by its milky sap that drips when a leaf is broken from its stalk.

When June arrives, I anticipate the day I spot the first monarch butterfly floating gracefully in the air.  Then I know it is time to enjoy one of my favorite hobbies—raising monarch caterpillars as they grow, and releasing adult monarch butterflies.  I am thrilled to count myself among the many monarch watchers who seek out and find the eggs from which a monarch caterpillar will eventually emerge.  Finding these conical shaped eggs that are smaller than a grain of rice marks the beginning of a wondrous cycle.  After hatching, the monarch caterpillars eat copious amounts of milkweed so they can grow, and create a chrysalis in which they will spend 10 to 14 days –waiting for wings until the day they emerge as adult monarch butterflies ready to be released.

If you would like to watch the process through which a caterpillar emerges as a butterfly, you may want to try rearing a few monarchs of your own.  Here’s how:  Find a suitable container for your caterpillars (or eggs).  You can use any large plastic container such as pretzels come in, or you may buy a container at almost any pet store.  Collect milkweed as a food source.  Placing the milkweed in moist floral foam seems to work well to keep it from drying out.  Cover the top of the container with cheese cloth (or old gauze curtains) secured with a rubber band to give the caterpillars air and keep them safe.  Keep the lid of the container to cover when transporting the container. Find monarch eggs or caterpillars and add them to your container.   Be prepared to clean the container and replenish milkweed often, especially as the caterpillars get larger and more active.  If you are starting with eggs, you may not see much at first.  However, soon you will start to see the frass, commonly known as caterpillar droppings, a sure sign you have monarch caterpillars.  Rearing monarchs lets you witness the caterpillar as it grows and sheds its skin.  It grows to many times its original size.  The final transformation from caterpillar to chrysalis is especially exciting as the full grown caterpillar sheds its skin for the final time, revealing a green-ribbed exterior that will eventually harden and become the smooth green chrysalis trimmed with a rim of gold along the edge that is the hallmark of the monarch chrysalis.  For more information on rearing monarchs visit  If you are curious about whether monarchs have been spotted locally, monarchwatch’s Facebook page is especially helpful.

Monarch rearing ends when the butterfly emerges and you release it into the wild.  Each time I release an adult monarch, particularly at the end of the season, I imagine how far away that monarch will fly as it (hopefully) migrates to Mexico for the winter.  To learn more about the monarchs’ extraordinary migration, a PBS Home Video The Incredible Journey of the Butterflies in DVD/Blu-Ray format, is available in the Mercer County Library System.  This DVD is possibly the next best thing to visiting the locales where monarchs overwinter.  However, if you wish to witness this mass migration in the fall locally, consider a day trip to Cape May in late September to early October when the migration peaks.  The Cape May Bird Observatory is home to the Monarch Monitoring Project, which is sponsored by the New Jersey Audubon Society.  Or consider contributing to conservation efforts by adopting a monarch for a minimum $25 contribution to support the Monarch Monitoring Project’s research and education programs. For more information, call the Cape May Point Bird Observatory (609)884-2736 or email  When you adopt a monarch, you receive a certificate detailing your adopted monarch, which will be tagged.  If the monarch you adopted is found in Mexico or along the way, the Monarch Monitoring Project will send you another certificate documenting your butterfly’s journey.

By now you might be wondering, why rear monarchs?  The truth is that these beloved butterflies are endangered due to declining habitat.  According to’s Monarch Waystation Program, “Unfortunately, the remaining milkweed habitats in pastures, hayfields, edges of forests, grasslands, native prairies, and urban areas are not sufficient to sustain the large monarch populations seen in the 1990s. Monarchs need our help.”  Go online or read more about monarchs to learn how you can help the monarch population.  Plant flowers and bushes to attract monarchs, add milkweed and you will have created a safe haven for the monarchs to breed as well as feed.   For more on butterfly gardening basics, visit the Master Gardeners of Mercer County’s website page dedicated to butterfly gardens.  The Mercer Educational Gardens is located at 431 Federal City Road in Pennington, NJ - home to both a butterfly garden and the Kate Gorrie Butterfly House.  Naturalist-led educational programs about butterflies are also offered at Duke Farms in Somerset County.

If rearing monarchs is not for you, local butterfly festivals and butterfly gardens provide many opportunities to observe monarchs up close.  Stony Brook Millstone Watershed Association will host two butterfly tea parties in July, in addition to the Annual Butterfly Festival on Saturday, August 10, 2013.  Another opportunity to view monarchs up close is at The Master Gardeners of Mercer County’s 11th Annual Insect Festival on September 7, 2013 from 1:00—4:00 pm at the Mercer Educational Gardens.  At this event “local naturalists and Master Gardeners will offer insect displays,” including the opportunity to see butterfly metamorphosis.   This event also features demonstrations of monarch tagging.  Monarchs are tagged as a means of collecting data about their migratory patterns.  According to’s Migration & Tagging Program, “Many questions remain unanswered about the fall migration of the monarch population east of the Rocky Mountains.”

Monarchs are one of the delights of summer.  Children’s books make a Waiting for Wings by Lois Ehlert is a beautifully illustrated non-fiction book about butterflies that is ideal for sharing with young children.  The last page features advice for growing a butterfly garden complete with suggestions of additional resources for more information.  Another recommended title for kids who want to learn more about monarchs is a National Geographic science reader Butterflies by Laura F. Marsh.  Butterflies is ideal to pair with monarchs on display, as it clearly explains the monarchs’ life cycle and helps answer the questions curious children ask when viewing monarchs up close.  Check out the many fiction and non-fiction titles in the library.  I hope you will come to share my delight in the natural wonders of watching the monarch caterpillar become a butterfly.
great accompaniment to the butterfly watching experience.

- Tracy Smith


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