Butterfly Extinction in Tennessee: The Native Plants That Actually Bring Them Back
If you are a Tennessee gardener wanting to help reduce the butterfly insect decline in Tennessee butterflies‚ plant Tennessee native host plants (like Butterfly Milkweed‚ Spicebush‚ and native Joe Pye Weed) instead of generic “butterfly bushes” sold at big box stores․ Tennessee is in a transition zone‚ as USDA Hardiness Zones 6b through 8a‚ where Monarch‚ Eastern Tiger Swallowtail‚ Zebra Swallowtail‚ and Spicebush Swallowtail breed‚ migrate‚ or overwinter․ Because of the role this state plays as a major corridor‚ what you plant here has an outsized impact․
It’s no longer a thought experiment; catastrophic declines like the greater than 80% Monarch drop since the 1990s are now well documented‚ including by the Xerces Society and the United States Fish and Wildlife Service․ Some are locally extirpated‚ such as the Xerces Blue and the Zestos Skipper of Miami․ Keep in mind that the news in national coverage just goes for the broad sweep‚ with federal listings or exotic coastal species the average home gardener here is unlikely to encounter․ The more practical regional question‚ for those in Nashville and Knoxville and rural Middle Tennessee‚ is what in the world do we put in the ground this year?
Why Tennessee holds more importance than people realize
Tennessee is also on the migratory path to Mexico for the Monarchs․ Monarchs migrating south in September and October need nectar to make the 2000-mile trip․ It takes more than a flower․ It must be flowering at the right time and have sufficient amounts of nectar․ Several late season natives like Joe Pye Weed and native Asters fill in․ Likewise‚ several resident spring and summer species like Zebra Swallowtail (Tennessee’s state butterfly) depend on Pawpaw trees․ No Pawpaw‚ no Zebra Swallowtails in that yard‚ period․
Nectar plants keep adult butterflies from starving to death․ Host plants keep the next generation going․ The garden you see in all those butterfly books (the ones with all the pretty flowers) is‚ effectively‚ a butterfly rest stop with no nursery attached․ There may be a few butterflies‚ but that’s all․
Species You’ll Actually See (and Lose) in the Southeast
Monarch - The best-known decline is because milkweed is mowed down in herbicide-intensive agriculture and paved roadsides․ No Common Milkweed and Butterfly Milkweed‚ no Monarch reproduction‚ full stop․ Caterpillars cannot eat anything else․
Eastern Tiger Swallowtail: Very common in Tennessee‚ but populations in urban and suburban areas have decreased due to the removal of Tulip Poplar and Wild Cherry for development․
Zebra Swallowtail - An entirely Pawpaw dependent species․ They are extirpated from areas where the Pawpaw understory has been removed for lawn or landscaping․
Spicebush Swallowtail - Spicebush or Sassafras caterpillars․ Both plants are commonly cleared in suburban backyards as ““brush‚”” quietly thinning the local populations of butterflies․
The Miami Blue‚ Karner Blue‚ and Mission Blue‚ all of which were non-native to Tennessee‚ are now extinct․ Their trajectories foreshadow the fate of less-studied regional species if host-plant habitat shrinks everywhere․
Building a Butterfly Garden That Works for Tennessee Conditions
When to plant: March or April‚ after the frost has melted‚ or in September or October‚ when the soil is warm‚ because Tennessee’s clay soil keeps roots from experiencing summer heat when they are young․
Choose a sheltered spot‚ butterflies need 6 hours of sunlight for feeding and flying and as cold-blooded animals they won’t eat or fly in the shade․ The garden should be in the sunniest part of the yard․ Fences‚ hedges‚ and shrub lines break the wind‚ which butterflies dislike․
Must have host plants to reproduce․
* Butterfly Milkweed for Monarchs - Orange flowering plant that thrives in dry or poor soil․ One of the few food sources for Monarch caterpillars․ * Spicebush for Spicebush Swallowtails‚ the native shrub is also a source of fall berries for birds * Pawpaw for Zebra Swallowtails: very slow to establish but critical for keeping this butterfly in your area․
Nectar plants (for adults‚ especially fall migrants):
* Joe Pye Weed - tall flowering plant‚ blooms from August until September‚ attracts migrating Monarch Butterflies heading south * Purple Coneflower - blooms all summer‚ drought tolerant once established * Black-Eyed Susan - Blooms reliably‚ low maintenance‚ and easy to grow for beginners
TN Nursery sells several of these as plants‚ not seed packets․ This is important because a Butterfly Milkweed Plant put in the ground 6-8 inches tall will often be set with caterpillars in its first year‚ whereas plants started from seed take an entire gardening year to reach a size where they can withstand being defoliated repeatedly by feeding larvae․
Water and shelter: Shallow bowls of wet sand and puddling spots give butterflies minerals not present in nectar․ Deep dishes may drown butterflies‚ so a shallower design should be used․ They may be seen upon flat stones‚ warming their wings in the morning sun․
What not to use: Any insecticide‚ even “organic” pyrethrins and insecticidal soaps․ These will kill off all caterpillars․ If you are treating lawn grubs or ornamentals‚ keep at least 15-20 ft (4․6-6․1 m) from any host plant or nectar-producing plant in your butterfly garden․
A Realistic Timeline
An initial‚ partial garden will take time․ Host plants such as "Paw
