Last spring we purchased and planted two species of milkweeds, Swamp Milkweed (Asclepias incarnata) and Butterfly Weed (Asclepias tuberosa), both host the monarch butterfly (Danaus plexippus). Altogether we planted approximately four plants. Every specimen was assaulted by tiny yellow-orange aphids, thus defoliated early in the growing season. In effect, this made the plants ineffective as hosts, as butterflies cannot deposit eggs on foliage that no longer exists. 

This spring we purchased and planted additional plants. Along the west side of our property we added two specimens of Swamp Milkweed and in our backyard, two Asclepias tuberosa. In addition to host plants we offer native plants which appeal to nectaring adults - for example, Hollow Stem Joe-Pye (Eutrochium fistulosum), Boneset (Eupatorium perfoliatum), etc..

The bright yellow aphids returned. And so we enthusiastically pinched together our thumbs and index fingers, and swiped the offenders off our plants (staining our fingertips, but saving our foliage!). By mid-summer our plants were all rather healthy - lots of leaves, plenty of blooms.

We began observing the return of our adult Monarchs in July. In August we noticed eager males pursuing females. The monarch courtship consists of two phases: aerial and ground. The aerial portion involves the male forcing the female to the ground, followed by copulation. Gee, what a romantic, huh?  Male monarch anatomy includes a pair of claspers that grasp the female during mating. We witnessed this courtship this year...and its culminating copulation. We discovered the attached butterflies while they were grounded; I was disappointed when they took flight and landed high in our 80+ year old blue spruce. I hurried inside to change my lens and was able to capture a couple of shots.


The male monarch can be positively identified by the scent patch on his hind wing. He is also larger than the female of the species.

Resource:, "Monarch butterfly," retrieved online September 17, 2017

Photo: © 2017 Jessica Allen



As mating became more frequent, we noticed female monarchs alighting on our Asclepias foliage, bending their abdomens gracefully toward the undersides of leaves and depositing single eggs.  


A female monarch butterfly will lay a single egg on the underside of a milkweed (Asclepias spp.) plant - usually near the top of the plant.

Cardenolide - found in the plants' namesake milky latex - makes Monarch caterpillars taste terrible and it is a potent toxin too!

Resource: "Milkweeds are Unwilling Hosts to Monarchs," by Jim Williams, published in the Star Tribune, July 11, 2017 - retrieved online September 17, 2017

Photo: © 2017 Jessica Allen

One evening we were sitting in our backyard - serving as an unwilling buffet for Asian tiger mosquitoes (Aedes albopictus) - when I glanced at the butterfly weed growing beside me and discovered a wee, tiny caterpillar! There...on the very leaf as that in the above photograph. The caterpillar was 9.5 mm in length - less than 1/2 an inch!

 Asclepias tuberosa appeared to receive most attention from our visiting females, but by late August  we noticed the swamp milkweed was receiving a lot of attention as well. One afternoon we counted twenty-eight caterpillars on two plants. The caterpillars ate, and ate, and ate...and grew and grew and grew. 

One afternoon in August, I spent four hours with a particular caterpillar. I discovered it clinging to a non-Aclepias leaf and wondered, What are you doing? I watched as the 2" caterpillar traveled down the stem, across leaf litter, across grass, up the stem of another non-host plant, down the stem, across a stump and finally, back to the butterfly weed on which it continued to dine.

Monarch Caterpillar feeding on butterfly weed (Asclepias tuberosa) in Lebanon County, Pennsylvania | ©2017 Jessica Allen

I learned to look for caterpillars in the leaf litter and traveling across our lawn. We began to refer to these excursions as walkabouts. A walkabout most often resulted in a caterpillar stopping and tucking into its characteristic indication the caterpillar is prepared to shed its skin, revealing its chrysalis.

A couple weeks ago I discovered a caterpillar in the J-formation hanging in our 'Brandywine' viburnum. It was dusk and a storm was predicted that evening. I was relieved to discover a beautifully-formed creamy pale green chrysalis the following morning...


Just before they pupate, monarch larvae spin a silk mat from which they hang upside down by their last pair of prolegs. The silk comes from the spinneret on the bottom of the head. As it sheds its skin for the last time, the caterpillar stabs a stem into the silk pad to hang. This stem extends from its rear end and is called the cremaster.

Resource: Monarch Lab, University of Minnesota, retrieved online September 15, 2017.

Photo: © 2017 Jessica Allen

Although I was ecstatic to discover the chrysalis I must confess I was a bit disappointed at having missed the transformation from caterpillar-to-chrysalis. I began paying close attention to the other caterpillars. It wasn't until Michael was painting our front porch that I finally got my chance to photograph the final shed.

One Friday evening we discovered a caterpillar in the J-formation under the railing of our front porch. I hoped he would remain that way until I had the opportunity to photograph him in natural light. I was so delighted to find him in the exact same position the following morning! He had not yet shed his skin.

I spent a total of four hours on the front porch and finally, spanning less than a single minute, his skin split. Click an image below to enlarge.

Although I wished to photograph the caterpillar's final shed in natural light, the sun was low in the sky behind my subject and the alternative (to re-position myself) left me standing in a flower bed between boneset (Eupatorium perfoliatum) and a porch railing...and so, I resorted to using artificial light (i.e. my D7200's built-in flash).  

The caterpillar hung motionless for a long time, only its filaments twitching occasionally. Suddenly, with little warning, the skin split down the caterpillar's back. The pale green chrysalis was now visible. As more-and-more chrysalis appeared more-and-more skin disappeared. As the caterpillar's skin folded up it began to look like a knotted heap of black threads. Finally, as if the caterpillar discarded his clothes, the heap fell to the porch.  

While the process of complete metamorphosis looks like four very distinct stages, continuous changes actually occur within the larva. The wings and other adult organs develop from tiny clusters of cells already present in the larva, and by the time the larva pupates, the major changes to the adult form have already begun.
— Monarch Lab, University of Minnesota

The chrysalis - at first - appeared bright yellow-green, somewhat bulbous and appeared wet. It was initially ridged, rather than the sleek and smooth pale green amulets I am used to finding in my yard. The beautiful gold design was not yet visible. According to entomologist Nancy Miorelli, "The crown of golden points – the diadem – doesn’t sparkle until after the first 24 hours of the formation of the chrysalis."

For a few moments, as I watched it, the chrysalis continued to if the caterpillar was getting used to his new outfit. I picked up its discarded skin and was surprised to discover it was soft and pliable. It felt as if it could be stretched out, but I did not attempt it. The caterpillar's feet (looking sort of like socks now) were visible, along with the now battered-looking filaments. It really did appear as if a caterpillar simply stepped out of its clothes...and in a sense, it did!

After experiencing this amazing transformation I was eager to witness the next phase: the adult Monarch emerging from the chrysalis. This final phase of metamorphosis is referred to as eclosing.  To photograph this, I returned to the chrysalis in my backyard (the one hanging from the 'Brandywine' viburnum).

I began to monitor it for signs it would soon eclose. Each day I took note of its coloration. Soon, it began to show visible darkening (versus the creamy pale green to which I had become accustomed). The chrysalis appears to darken as the pigments in the adult's wings become visible.

Just before the monarchs emerge, their black, orange, and white wing patterns are visible through the pupa covering. This is not because the pupa becomes transparent; it is because the pigmentation on the scales only develops at the very end of the pupa stage.
— Monarch Lab, University of Minnesota

On the morning of September 11, 2017 my twelve-year-old son and I discovered very clear evidence the chrysalis on our 'Brandywine' viburnum was ready to open. We began our vigil around nine o'clock and remained patient through what became an unseasonably hot afternoon. As the hours passed the chrysalis appeared more and more transparent (although, as you read above, that is not literally true). Finally, after my son and I had given up hope - and he had gone inside - the chrysalis began to open...and within less than one minute, the adult butterfly emerged! Click an image below to enlarge...

The newly emerged female Monarch awkwardly maneuvered around on the viburnum until she found a roomy place to spread her wings. She opened and closed them until the wrinkly, vulnerable-looking black and orange wings straightened out and began to harden. Within an hour she had climbed to the uppermost stem and within three hours, she lifted off and flew away.

It has been one full week since I witnessed the fascinating transformation of a Monarch butterfly. Since that time we have sheltered five chrysalises, bringing them indoors after discovering two casualties (victims of a spider's web). This morning we released two adult females. We are eagerly waiting for the eclosing of the three additional chrysalises. Adult butterflies are still mating in our Pennsylvania backyard and the butterfly weed is still green (although the swamp milkweed has gone to seed). Yesterday afternoon I re-located one caterpillar to a fresh supply of Asclepias tuberosa and spotted another setting off on his walkabout.

Our conservation efforts of the Monarch butterfly would not have been possible without generous grants from the Jane Goodall Institute and Roots & Shoots. These organizations are solely responsible for funding the purchase of healthy specimens of Asclepias tuberosa and Aclepias incarnata. And if not for the efforts of the Brandywine Conservancy, we would not have had the opportunity to procure robust, locally grown plants that immediately contributed to our efforts to strengthen Monarch populations. 

Photographers deal in things which are continually vanishing and when they have vanished there is no contrivance on earth which can make them come back again.
— Henri Cartier-Bresson

If you are interested in helping the declining North American Monarch population, consider purchasing and planting healthy milkweed species. Research which varieties have been determined to grow successfully in your part of the country and plant them during the appropriate time of year for your growing zone. To aid you, the Xerces Society has collected a number of resources HERE.