Springtime Sighting of a Vulnerable Butterfly, the West Virginia White

by | Environment

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On the far edge of western Massachusetts, the roads wind around beautiful hills and cobbles of a small town. 

In the 1800s, this town made its name on agriculture and small industry. Today, meadows are maintained to allow cattle to graze, and farm stands full of vegetables line the narrow roads. The residents continue their family businesses as small-scale farmers and ranchers. 

Looking at the architecture, it’s easy to feel like you’ve been transported back in time. Passing by historical homes along the road to the trailhead, there are beautifully pristine farmhouses with white siding and old country porches next to abandoned cobblestone cottages of someone’s homestead from long ago.  

Author‘s Note: To ensure the safety of the populations discussed, locations and names are kept vague.

Meeting a Small Butterfly in Western Massachusetts

One spring morning, eight botanists packed into carpools and drove to this small town. We parked our cars and gathered around, pausing only to look at the roadside plants and tree swallows dancing in the field across from us.  

On one side of the street, we saw violets of every color, a sign that spring was just beginning. To the other, a massive cluster of large-flowered bellwort (Uvularia grandiflora) sprouted from the roadside gravel. This species was a treat to see along in such numbers, as in many New England states, it is considered extremely rare or uncommon. 

After spending a few minutes admiring these plants, we walked further. Pitched against the steep mountainside were several stones placed as a haphazard staircase. We all checked our backpacks, sprayed our shoes, and readied notebooks or cameras. The trailhead itself was nothing more than a steep, rocky incline into the woods, but the plants we were here to see weren’t along the road. They were much further up the mountain.  

After a quick scramble, we began our hike with many pitstops to observe the uncommon – or just plain interesting – plants along the trailside. As we walked, our guide for the afternoon began pointing out plants with enthusiasm. 

The pathway narrowed, and we could only follow in a single-file line. We scrambled to keep up and remain in earshot while we took notes. Jotted onto my own notepad from observations that afternoon is everything from blue cohosh (Caulophyllum thalictroides) and fragile fern (Cystopteris fragilis) to Canada violet (Viola canadensis) and Goldie’s fern (Dryopteris goldiana).  

As we continued to trek upslope, our guide described a small butterfly that we should keep a look out for. This small white butterfly is known as the West Virginia White, sometimes also called the Toothwort White (Pieris virginiensis). The chances of seeing it were slim, but we kept our eyes peeled for anything that might flutter by.  

A Struggling Species: West Virginia White, Pieris virginiensis

The West Virginia White butterfly flies in the spring months of April and May, thriving on the spring ephemerals that populate rich, mesic forests.  

Once common across the Appalachian and Great Lakes, the butterfly is now considered imperiled. Forest fragmentation, invasive species, overpopulation of deer, and development all threaten its existence. Even as we walked through what looked like mature woods, we could hear the faint sounds of a tractor levelling a freshly logged parcel for a new house.  

Every hundred yards, our guide pointed out yet another imperiled or uncommon plant trailside, and we stopped to take photographs and notes. This was the cadence for the afternoon, and unlike a hike for the purpose of summitting, our destination was truly the journey. These woods were abundant with rare or uncommon species, which meant we would take our time, only turning around once we were ready for break for lunch.  

Every hundred yards, our guide pointed out yet another imperiled or uncommon plant along the trailside, and we stopped to take photographs and notes. These woods were abundant with rare or uncommon species, which meant we would take our time on the trek up this mountain. Often, there were just one or two plants clumped along the trail or just in sight, but in some cases, there were so many plants we had to take a step back to appreciate the value of the landscape.

Often, there were just one or two plants clumped along the trail or just in sight, but in some cases, there were so many plants we had to take a step back to appreciate the value of the landscape.  

We hadn’t forgotten about the butterfly, either. The West Virginia White is a small, white butterfly with delicate wings. If it stops long enough to be seen up-close, you’ll notice its fuzzy body is a gentle greyish blue. 

Though it looks fragile, this butterfly is part of a critical link in the ecosystem. It is a native species to North America, prolifically pollinating plants throughout early spring so they can continue to grow the following year. 

As we walked along the trail, we kept an eye out for fluttering wings. Many people were beginning to feel less than optimistic about seeing the butterfly, but happy to see more common pollinators along the trail. Others were preoccupied with taking photographs or notes of the plants along the trail, content with the other rare species spotted for the day.  

All attention turned when someone shouted, “There it is!” 

Fluttering through the ferns and blooming violets and spring beauties was a West Virginia White. It flew by too fast to snap a photograph, but everyone was in awe of seeing such an endangered species in the wild. Compared to many common species it was surprisingly small; hardly any bigger than the delicate spring flowers it fluttered past. 

Once the butterfly was out of sight, we all took a moment to reflect. Not only were we seeing rare plant species, but now we were beginning to see rare relationships in the ecosystem.  

The butterfly kept appearing as we walked, fluttering just fast enough to keep us from getting a photograph. We were getting closer to where the butterfly preferred to fly, which could only mean we were getting closer to its host plant.  

The Toothworts, Cardamine concatenata and Cardamine diphylla 

While the butterfly pollinates a wide range of plants in the forest understory, it depends primarily on two closely related plants to reproduce, which we were on the lookout for. These host plants are essential to the developing caterpillar, and the butterfly seeks it out specifically to lay its eggs.  

This is where the Toothwort (Cardamine concatenata) comes into the picture. As a small plant with slender, warm green leaves, it doesn’t stand very tall on the forest floor. Each stalk ends with a splash of gentle, four-petaled flowers.  

The other closely related plant is the broad-leaved toothwort (Cardamine diphylla). With broader leaves, it has the same characteristic white petals and warm-green coloration and does not differ much from C. concatenata, which is extremely rare in most New England states. According to NatureServe, this plant is either critically imperiled or vulnerable throughout New England and eastern Canada.

The West Virginia White depends on toothwort as a source of food during its caterpillar stage. This means that the parent butterfly must lay its eggs on the plant, as the caterpillars need to start eating as soon as they emerge. If the caterpillars can’t find food, they will quickly starve. This urge for the parent butterfly to lay its eggs on a specific host plant has been ingrained over generations, fine-tuned through the evolutionary process. 

“West Virginia Whites need a steady supply of toothwort, a spring-blooming plant, to eat in its larvae stage.”
- Canadian Parks and Wilderness Society Ottawa Valley Chapter

One of the many plants we were there to see that day was the toothwort, which primarily grows in rich, mesic forests. These are the same forests where you will find the West Virginia White. Unfortunately for our tired feet, it also thrives in upland forests, which meant we had more hiking to go before we saw the plant. Still, with the butterfly guiding our way, we were feeling optimistic. 

Our guide had been to this forest plenty of times before and knew these plants like the back of his hand. Still, we kept our eyes peeled knowing the small plant could be around any corner.  

The trail was a series of loose dirt switchbacks, and every couple hundred yards we would come across another plant of interest that our guide would point out. Being eager botanists, we would eagerly take turns observing up-close. In some areas, the trail could fit three or four of us at a time, each group discussing the form of the plant, its current health, or pollination strategies. 

Highlights (below) include a Canada violet (Viola canadensis) that stood over a foot tall, making it the largest violet I have seen yet. Around another bend stood a red trillium (Trillium erectum) which I only ever think of as “dog trillium” as it smells like a wet dog that just splashed around in a stagnant marsh. Other common names for this plant include “Stinking Benjamin” as the putrid odor is meant to attract carrion flies and beetles. 

As we crested the hill, our guide pointed out another plant. This one we had been waiting for: the toothwort. Specifically, we were standing in front of Cardamine diphylla in full bloom.  

Leaning down to take photos, we savored the moment as the butterfly flitted by yet again. It had found its host – a single plant living in the entire forest. Other plants, like the dutchman’s breeches (Dicentra cucullaria) and blue cohosh (Caulophyllum thalictroides), seemed to grow abundantly along the trail’s edge. This flower was set away from the path and presented a single stalk across the whole landscape.  

Life In Action

Once we made it back down the mountain to the roadside, we decided to break for lunch. We surveyed the road for a moment before picking out a small gravel pull-off where we could all sit.  

While the gravel presented hardly enough room for a car to pull over, it accommodated the eight of us as we sat on the gravel, along rocks and logs, or laid across our backpacks. 

Behind us, there was sheer downhill with a trail that we would explore after the break. Next to us stood the patch of bellwort (Uvularia spp.) that we admired at the beginning of the trip, a fine view for the afternoon’s lunch. 

Each of us brought a portable lunch, though it’s not uncommon or unwise to over-pack when it comes to food. Whoever had extra to share tossed their food into a communal snacking pile. Making idle chat as we ate, the communal pile grew. Soon, everyone had their fill of hummus, carrots, chocolates, dates, trail mix, and cheese. 

Seeing the butterfly had me thinking about the benefits of each species on the landscape. Without pollination, most of the flowers we saw on our hike would not exist. Without pollination, flowers don’t form fruits, and without fruits, they don’t form seeds.  

Some flowers can pollinate themselves, but it’s a backup strategy to give them time. It doesn’t leave the next generation healthy or genetically secure.  

Plants rely on the relationships they form with the ecosystem, either in the weather patterns or in other species, to carry on their lineage. Likewise, the other species rely on the plants for a source of shelter or food so they can carry on their lineage. Without one or the other, the ecosystem is broken.  

In fact, many species in the early spring landscape of this forest existed because of a single plant and two butterflies in a vast forest. The West Virginia White will visit other plants to pollinate them, but they rely on Cardamine spp. to feed their young.  

As we ate and discussed the plants of the day, a flutter of white passed by. The conversation continued, but I scrambled for my camera as I had been determined to get a photo of the elusive butterfly.  

Eagerly grabbing my camera, I knocked over my backpack only to discover my tick spray bottle had come loose. On the bright side, it is unlikely that I would have to deal with ticks in my backpack ever again. 

What ensued in the next five minutes was a comedic chase in the background of the group’s conversation. The butterfly stayed near the group, but every time I got close enough to focus the camera, it would flutter away again.   

Soon, the butterfly settled down briefly enough for me to take a photograph. 

It arched its body upward, and to my surprise, another butterfly responded to it.  

Obviously, it wasn’t staying still for me.  


The photographs were blurry with surprise in the few seconds everything occurred in, but what they show is the continuation of life for this species. 

A Garlic Mustard Invasion

While fragmentation of habitat is a prevalent problem for many plant and animal species of the modern world, there is another that is much quieter, but much more deadly for the West Virginia White.  

Invasive plant species are taking the fight to the butterfly’s home, taking advantage of the relationships that have existed on this land for years.  

Garlic mustard (Alliaria petiolata) is an invasive flowering plant with an allelopathic strategy. This means it wages a kind of chemical war with other plants in the competition for growth and sunlight. The plant releases compounds from its roots that prevent other plants from growing, effectively poisoning the ground it grows in, preventing other plants from competing for sunlight and root space. 

Garlic mustard is one of many invasive plants that are causing trouble, but it is particularly destructive to these habitats as it lowers the diversity of plant species, which then harms the diversity of animal species.

Evolutionary Relationships 

For the West Virginia White, the destructive powers of garlic mustard go a step further: 

Garlic mustard and the Toothwort are in the same family, which means they give off distinctive scent patterns to the butterfly. (2) Unfortunately, garlic mustard is not a native species to North America, which means the butterfly has not evolved to understand these slight differences. To the butterfly, it all looks like the same plant. As a result, the butterfly is equally attracted to garlic mustard’s scent, mistaking it for the scent of Toothwort.  

For the imperiled butterfly ready to lay its eggs on a host plant, life is difficult. Not only is the plant rare, but it must hope that the habitat has not been disturbed and the plant is still growing. It searches out those scent patterns. 

With the quick spread of garlic mustard, the butterfly has not had time to evolutionarily adapt to these new signals. In its home forest, it is more likely to find garlic mustard than it is to find Toothwort, as garlic mustard spreads rapidly; as much as 20 feet per year.  

If the butterfly lays its eggs on garlic mustard, the larvae will not develop and many of the caterpillars perish before they can emerge. For the few who do survive, they emerge and begin eating, only to discover the garlic mustard is fatally toxic.  

A Reason for Conservation

As we walked down the lower trail, we came across a field of garlic mustard hidden in the forest. Here, there were hundreds of plants. The contrast was jarring, compared to the single toothwort plant we had seen in the upper forest.  

The pollinator researcher in the group quickly spotted two West Virginia White butterflies fluttering around this patch of garlic mustard and began shooing them away. These butterflies were only looking for a place to lay their eggs and had no way to know these plants were not just a ripe field of food for their offspring. Many of these butterflies exist in isolation with small populations. It was easy to see that these garlic mustard fields were dangerous, causing local extinctions that could spread to the remaining West Virginia Whites. We all got to work pulling and snacking on garlic mustard.  

Garlic mustard must be removed before it sets seed, as the seeds are prolific and can last in the soil bank for 10 years. Because of this, it’s important that sites are frequently re-visited for management as well, to exhaust the seed production year after year.  

The root and plant material must be removed in all, and it cannot be left on the ground or in sunlight as it will continue to set seed every once removed from the ground. After a half hour, each person had pulled armfuls of garlic mustard. We found an abandoned camping pallet to store the plant material under, hiding it from sunlight and removing it as far as we could from the soil.  

Conservation isn’t about a single species.  

Conservation is about the preservation of the ecosystem and all the relationship ties that come with it.  

Whether that starts with a specific species, or on a broad ecological scale, everyone has the power and ability to do something good. 

Even if pulling garlic mustard that day bides a little bit of time, it gives those butterflies another generation to live. That is what makes the work worth it. 


  1. Canadian Parks and Wilderness Society Ottawa Valley Chapter, https://cpaws-ov-vo.org/what-you-need-to-know-about-the-west-virginia-white-butterfly-species-at-risk-series/
  2. Davis SL, Frisch T, Bjarnholt N, Cipollini D. How Does Garlic Mustard Lure and Kill the West Virginia White Butterfly? J Chem Ecol. 2015 Oct;41(10):948-55. doi: 10.1007/s10886-015-0633-3. Epub 2015 Sep 23. PMID: 26399433.



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About Destynnie K. Berard
I am a lifelong naturalist who believes a good sense of humor is essential to staying happy. ★ After traveling for years, I settled in New England, falling in love with the diverse landscape the Northeast has to offer, and began pursuing conservation in earnest. ★ My career background is in enterprise marketing and communications, which provides me with a unique perspective of ecological relationships.


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