Guest post by Ryan Scanlon with Q&A Landscaping. Q&A supports native biodiversity by installing hundreds of native flowers, shrubs, & trees every year.
With the unending naturalization of imported plants, planting native bushes and perennials are important in sustaining (and saving) natural wildlife. But, there could be more light shed on planting specific hosts that harbor only one or very few species.
In this blog, we’ll discuss 7 species of plants native to Western Pennsylvania that are exclusive hosts to one or very few butterflies. This is so more gardeners can be aware and have a conscious effect on supporting native life cycles & wider food chains.
We’ll start with a common relationship between pollinator & host that any insect or native enthusiast will know:
1. The Monarch Butterfly & its host, the Common Milkweed
One of the most famous mutualistic relationships in the pollinator world is of course the Milkweed & the Monarch. The caterpillar of this butterfly feeds exclusively on Milkweed (Asclepias syriaca) for the entirety of its larval stage.
Milkweed equips the Monarch (Danaus plexippus) with toxins that make caterpillars and adult butterflies toxic to predators, who have evolved to leave them alone because of it. Of course, the monarchs help pollinate the milkweed flowers in return, as they move from plant to plant.
Growing Milkweed
To cultivate milkweed in your garden, choose a sunny spot with well-drained soil. Plant seeds or a whole bush in the fall or early spring, and water them regularly until the plants are established.
Once mature, milkweed is relatively low maintenance, & can spread aggressively. To control its spread, you can remove seed pods before they open. Providing a dense spot of milkweed can help your local Monarch population and native birds too.
2. The Spicebush & its host, Spicebush Swallowtail
The Spicebush (Lindera benzoin) supports the Spicebush swallowtail (Papilio troilus) in a similar way to our first partnership. This swallowtail relies heavily on the spicebush to support its offspring. Each larva exhibits two distinct eye-like markings that could be mistaken as a little snake by potential predators.
Photo by Jerry F. Butler, Entomology and Nematology Department, University of Florida.
To cultivate spicebush in your garden, plant it in a location that offers partial to full shade and moist, well-drained soil to offer a bright burst of yellow in spring and fall. Like all natives, if planted in optimal conditions, the Spicebush should be low-maintenance once established, but it does benefit from regular watering (especially in dry periods). Prune the plant in late winter to maintain its shape and encourage new growth.
3. The Endangered Karner Blue Butterfly & its only larval host, the Wild Blue Lupine
By Hollingsworth, J & K – U.S. Fish & Wildlife Service National Digital Library: WO-5309-020, Public Domain
The beautiful but endangered Karner Blue Butterfly (Lycaeides melissa samuelis) relies solely on the Wild Blue Lupine (Lupinus perennis) to provide for its larvae. The marriage between the two is intimate, but failing. Isolated, low motility populations have left the Karner Blue harshly exposed to habitat encroachment (by man and tree) along with rising temperatures.
Forest gain and thickening actually depletes the habitat of our pair here by shadowing-out open meadow. Their lowlands depend on regular disturbance of wildfires and may benefit in increasingly hotter years, where there will be no shortage of flames.
Seeds for this flower are not too hard to get your hands on; the butterfly itself is much rarer the lower the latitude.
Plant Wild Blue Lupine in full sun, optimally in well-drained, nutrient-poor soil. They do best in habitats that mimic its native surroundings, as in open fields and forest edges.
The Karner Blue Butterfly is believed to be extirpated, or no longer appearing naturally in Pennsylvania. Happily, it is recovering well in some areas. The planting of the Wild Blue Lupine can still help other native wildlife, though, and maybe provide a lifeline for the Karner Blue Butterfly if it were ever to blow back in on a gail.
4. The Pipevine Swallowtail and its host, The Dutchman’s Pipe
The Pipevine Swallowtail (Battus philenor), a beautiful velvet-blue and black-winged butterfly, relies exclusively upon the Dutchman’s Pipe (Aristolochia californica) to harbor its larvae. Said host is a vine, often called the pipe vine or the Dutchman’s pipe vine, with some stranger parts than the other native plants mentioned.
The dutchman’s pipe’s name comes from the abnormal shape of the mature flower parts, looking much like a pitcher plant. The larvae of the Pipevine swallowtail feed regularly on young parts of the plant, but the adult butterflies are incapable of returning the favor via pollination.
The Dutchman’s pipe peculiarly attracts flies and smaller pollinating insects down their cavernous one-way flower. Once it has forcefully guided a worthy candidate down to its stamen, the flower releases and allows the fly to exit with its pollen.
If you want to plant the Dutchman’s pipe vine, do so in a moist, wooden area, over a trellis, or by a stream. Expect vigorous climbing and some emergence of the Pipevine Swallowtail.
5. The antics of the Viceroy Butterfly & the Pussy Willow
(Not a monarch)
The Pussy Willow (Salix discolor) is our first tree of the hosts named so far. It serves as a nursery for the Viceroy butterfly (Limenitis archippus), which primarily deposits its eggs on the leaves and stems of this native willow species. Salix discolor is well-adapted to moist environments and frequently found along water bodies, providing an optimal habitat for the Viceroy’s life cycle.
The mimicry of the Viceroy serves as a defense mechanism against predators, which forgivably mistake it for the would-be toxic Monarch. The Viceroy Butterfly is codependent evolution exemplified in this three way relationship- its extant characteristics forged through millions of years of selection alongside the Pussywillow and Monarch.
6. The Baltimore Checkerspot & The White Turtlehead
Photo by Thomas Elliott on Unsplash
With the sixth pick of the butterfly & host draft, the adult Checkerspot butterfly (Euphydryas phaeton) selects the White Turtlehead (Chelone glabra) as its coevolutionary partner. The wild Checkerspot is the state insect of Maryland, supporting their pro baseball team in appearance.
Photo by Prairie Nursery
The White Turtlehead attracts mostly bumble bees to its blooms. The host thrives in damp meadows and along stream banks, with its creamy white flowers. They do well in full to partial sun. It may be hard for this plant to thrive without simulating or adding to a wetland environment.
7. New Jersey Tea & the Spring Azure Butterfly
Photo by Prairie Nursery
The New Jersey Tea (Ceanothus americanus) is a native shrub that gets its name from its use as a substitute for tea during the Revolution (we threw it all in the harbor). Its beautiful blue and eventual white clusters attract pollinators far and wide, and harbors the young of the Spring Azure.
The feeding of the Spring Azure (Celastrina ladon) caterpillars on the parts of this plant can be seen as healthy pruning, allowing sun to reach the lower parts of the plant.
Go plant some natives!
This blog post explores the critical coevolutionary relationships between butterflies and their host plants in Western Pennsylvania. These partnerships show how insects and plants have evolved together and rely upon each other’s mutual benefit.
Gardeners can easily incorporate these native plants to support local ecosystems. In the modern day, it’s ever-important to reinforce native habitats, to supply nature with nature, and to enjoy the beauty and benefits of these coevolutionary relationships in our own gardens. Q&A Landscaping installs native flowers, trees, and shrubs in Pittsburgh and can help start your native journey!
Sources:
https://entnemdept.ufl.edu/creatures/bfly/spicebush_swallowtail.htm
Hollingsworth, J & K – U.S. Fish & Wildlife Service National Digital Library: WO-5309-020, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1216948
https://www.prairiehaven.com/?page_id=9471
https://www.recordonline.com/story/news/2017/07/20/ny-endangered-karner-blue-butterfly/20111299007