Yucca filamentosa: Vital to Yucca Moth and Giant Skipper, Favored by Black-Chin or Broadtail Hummers

Yucca filamentosa is most commonly known as Adam's needle.

This memorable New World native has endeared itself beyond its native range, living comfortably throughout the world in a dazzling array of geographic and climatic settings. Universal popularity has bestowed numerous common names upon Yucca filamentosa.

Adam's needle is native to 29 states from the eastern seaboard westward into the Great Plains: Alabama, Arkansas, Connecticut,Delaware, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Mississippi, Missouri, North Carolina, Nebraska, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia, West Virginia, and Wisconsin.

Adam's needle is native to only one county in two states:

• Sussex County in southern Delaware and
• Kent County in central Rhode Island.

Adam's needle favors dry, sandy soils which, with a circumneutral pH (6.5 to 7.5), are neither too acidic nor too alkaline.

With its inherent resistance to drought and heat, Adam's needle basks in sunlight.

Preferred habitats are open areas such as open or thin woods, hills, and prairies. Also bluffs and rocky or sandy coastal areas entice Adam's needle.

Adam's needle responds well to cultivation. Yucca filamentosa blends beautifully into private and public landscapes, especially in garden or parking lot borders and in rock gardens. Adam's needle thrives in xeriscapes (Greek: ξήρος, xeros, "dry"), which minimize supplemental watering. Furthermore, Adam's needle joyously accepts confinement in pots or urns.

As an adaptable and hardy perennial (Latin: per, "through" + annus, "year"), thereby with a lifespan of more than two years, Adam's needle enjoys life, which is evinced in its willingness to spread beyond the comfort zone of its native range and habitat.

Moreover, Adam's needle propagates from seeds and from root cuttings. Also, Adam's needle sends out communities of hardy, viable offshoots.

The U.S. Department of Agriculture Plant Hardiness Zone Map, which classes plants according to the coldest temperature at which they remain viable, places Adam's needle in Zone 6 (-10° to 0° Fahrenheit, -23° to -18° Celsius) to Zone 10 (30° to 40° F., -1° to 4° C.).

Long, thick underground stems firmly anchor Adam's needle deep into the earth. Above the ground, basal leaves swirl circularly out and up to form a rosette around a central point. Leaves are grey green or blue green. Stiff and sword-shaped with sharp, pointed tips, leaves have a width of less than an inch (2.5 centimeters) and a length range of almost 12 to 30 inches (30 to 76 centimeters).

Long, curly, filamentous threads dance along the margins, or edges, of the leaves.

Proviso: if it looks like a sword, it might very well cut like a sword:

The sharp, pointed tips of the sword-shaped leaves, which defensively encircle the floral stalk with its life-perpetuating seeds, are capable of gashing and slashing with the most finely sharpened rapiers. Certainly children should be discouraged from playing with these potentially injurious leaves. Adults also should realize that Adam's needle leaf tips may draw blood from even calloused bare skin.

A stout, floral stalk rises from the center of the rosette. Sometimes towering to well over 6 feet (2 meters), the stem spurts forth loose clusters of one dozen to two dozen bell-shaped flowers from late spring to midsummer or late summer. Each flower is suspended from its own pedicel (Latin: pediculus, "little foot"), a little stalk which branches from the peduncle (Latin: pedunculus, "footstalk"), that is, the main stem. Flowers hang downwards, nodding approvingly with the welcome breezes which cool midsummer's escalating heat. Flowers have a width of about 2 to 3 inches (5 to 8 centimeters).

Petals are ovate (Latin: ovum, "egg") with an oval shape broadened in the base. The striking coloration ranges from predominantly creamy white to occasionally pale yellow white. Oftentimes red brown tinges delicately enliven the pure creaminess.

During their florescence (Latin: florere, "to flower, to bloom") --- their blooming time --- Adam's needles never close their petals. As lovely as their flowers shimmer in sunlight, the very essence of their creaminess glows in moonlight. The evening glory of these flowers is enhanced by a sweet fragrance which is released with intoxicating, beguiling intensity between dusk and dawn.

Somewhat elliptically shaped, each fruit capsule reaches a length of 1 to 2 inches (2.54 to 5.08 centimeters) and has a diameter of about 3/4 inch (1.9 centimeters).

Fruit capsules are compartmented generally into four to six locules (Latin: loculus, "little place"), which are small seed-containing cavities.

Fruits exchange the greenness of birth for the chartreuse of youth. Shades of tan brown or occasional blackness signal maturity in autumn.

Fruit capsules are dehiscent (Latin: dehiscere, "to gape, open, split down"), meaning that they open at maturity to release the enclosed seeds.

Fruits encapsulate 120 to 150 small, black seeds. Each seed measures around one-third of an inch (1 centimeter).

Yucca filamentosa seeds are made to fly and to travel afar. These seeds easily hitch a ride with the slightest breeze for wind dispersal to parts known and unknown, close and distant.

Yucca filamentosa enjoyed high status as ceremonial medicine with the Cherokee, Native Americans linguistically affiliated with the Iroquoian language family. Referring to themselves as Tsalagi ( ᏣᎳᎩ), meaning "principal people," Cherokees originated anciently in the Great Lakes region and established their homeland in the southeastern United States, primarily in the Carolinas, Georgia, and eastern Tennessee. 

Along with broom sedge (Adropogon virginicus) and amaranth (genus Amaranthus), Yucca filamentosa was an essential ingredient in green corn medicine. The Green Corn Festival was a harvest ceremony of major importance to Cherokees. Ethnologists noted that in the mid-twentieth century a curative component of the Green Corn Festival was still performed, although only as an individual household function and no longer as a community event.

The curative rite entailed drinking an emetic (Greek: εμετικος, emetikos, "causing to vomit") which prevented the colic caused by eating green corn. The colic itself resulted from stomach and intestinal worms laid as eggs --- up to 1,000! --- in the silky tassels of unripened corn by the green corn earworm moth (Helicoverpa zea). The emetic was prepared by steeping in warm water the leaves of Adam's needle, along with three or more other plants, after first hand crushing the foliage, which were then pounded together in a mortar.

Adam's needle was used as a dermatological aid by the Catawba and the Cherokee. The Catawba, also known as Esaw or Issa (iswä, "river"), whose homeland was along the border of North and South Carolina, rubbed the root directly onto the body to treat skin diseases. Roots also were decocted by mashing and then boiling to form a concentrated extract of its essences. The Cherokee pounded the root into a salve for sores.

Adam's needle served as an orthopedic aid for the Nanticoke (Nentego, "tidewater people), who migrated from the region of Labrador in eastern Canada to establish their homeland along the Chesapeake Bay, especially in Delaware and Maryland. The roots were mashed with warm water into a poultice which was applied to sprains.

The Cherokee treated diabetes with an infusion (Latin: infundere, "to pour into") of Adam's needle steeped in hot to boiling water.

The plant's fruit and lovely flowers were eaten fresh. Flowers were also cooked.

Roots were boiled and pounded for their abundant saponins (Latin: sapo, "soap" + -inus, "of or pertaining to") to make soap.

Because saponin is piscicidal (Latin: piscis, "fish" + cidium, "killing, cutting"), that is, poisonous to fish, the pounded roots were tossed into fishing waters to assure successful catches. Stupefied or lifeless fish floated to the surface for easy retrieval.

The strongest fibers of any native North American plant are found in the leaves of Yucca filamentosa. Native Americans split the leaves into long strips, which were then twisted into strong cords. Baskets, fishing lines, fishing nets, and even clothing were constructed from Adam's needle cordage.

Not only does Adam's needle play well with others, but Adam's needle is the playground! Adam's needle and the Yucca moth (Tegeticula yuccasella) are the Siamese twins of the natural world. Additionally, other inveterate devotees include:

• black-chinned hummingbird (Archilochus alexandri),
• broad-tailed hummingbird (Selasphorus platycercus),
• Cofaqui giant skipper butterfly (Megathymus cofaqui),
• Yucca giant skipper butterfly (Megathymus yuccae).

Archilochus alexandri is commonly known as the black-chinned hummingbird. Its species name, alexandri, was decided by French naturalist Jules Bourcier (1797 - March 9, 1873) and French entomologist and ornithologist Martial Étienne Mulsant (March 2, 1797 - November 4, 1880) in 1846. The French scientists selected the name to honor Dr. Alexandre, a physician who practiced in Mexico. Dr. Alexandre's passion was collecting birds and sending exotic specimens to Paris. As such, the first known specimen of the black-chinned hummingbird was captured by Dr. Alexandre in the Sierra Madre in western Mexico.

The vast breeding habitat of black-chinned hummingbirds encompasses western North America from south central British Columbia to the northern regions of the north Mexican states of Baja California, Chihuahua, and Coahuila. In the United States, this habitat stretches across eastern Washington, central Idaho, western Montana, southwestern Wyoming, southeastern Colorado, and southwestern Oklahoma. Black-chinned hummingbirds also stake their claims to the striking panorama from coastal California to central Texas.

A snowbird, the black-chinned hummingbird shelters from winter's roarings in the southern sectors of the states of Arizona and California and along Mexico’s Pacific slope from northwestern Sonora to the south central state of Morelos.

The black-chinned hummingbird measures about 3.25 inches (8.25 centimeters) in length.

These minuscule hummingbirds have metallic-green colored backs and crowns. A white spot behind their eyes is noticeable on their black faces.

With a black chin and upper throat, males have an iridescent blue-violet lower throat bordered below by a white collar.

In addition to Yucca filamentosa, black-chinned hummingbirds favor honeysuckles (genus Lonicera), nasturtiums (Tropaeolum majus), and scarlet delphiniums (Delphinium cardinale).

Selasphorus platycercus is commonly known as the broad-tailed hummingbird.

The open freedom of high altitudes, at elevations up to 12,700 feet (3,871 meters), is enticing to broad-tailed hummingbirds.

In the United States, broad-tailed hummingbirds nest in the western states of Arizona, Colorado, Idaho, Nevada, New Mexico, and Wyoming. Breeding also occurs in extreme western Texas near the border with the north Mexican state of Chihuahua.

A subspecies, Selasphorus platycercus sedentarius (Latin: sedentarius, from sedere, "to sit"), resides in central Mexico.

These snowbirds usually overwinter from northern Mexico to northern Guatemala.

Broad-tailed hummingbirds usually measure 4 to 4-1/2 inches (10.16 to 11.43 centimeters) in length.

Iridescently backed and crowned in regal emerald coloring, broad-tailed hummingbirds have white breasts.

A gorget (Old French: gorgete, diminutive of gorge, “throat”), that is, throat, of metallic iridescent rose coloring distinguishes the males.

In addition to Yucca filamentosa, broad-tailed hummingbirds preferentially extract nectar from delphiniums (genus Delphinium), penstemons (genus Penstemon), and salvias (genus Salvia).

Megathymus yuccae is commonly known as Yucca giant-skipper butterfly.

Yucca giant skippers have western and southeastern populations in the United States. Western populations flit from the west coast east to Nebraska and Texas. Southeastern populations hail from southeastern Virginia south to southern peninsular Florida and west to Arkansas and Louisiana.

A host plant for Yucca giant skippers, Adam's needle is a critical participant in every stage of this flying insect's life. Amber-brown eggs are deposited on the leaves. Tea-colored caterpillars with reddish brown heads lighten and whiten after a few months, confidently nibbling on leaves and boring into the roots. As they consume root chunks, the caterpillars also make a silk chimney which projects up from the root and which serves as their winter burrow. Pupating within the burrow in late winter or early spring, the chrysalids roam up and down, secure and safe therein. In the final stage of life, the Yucca giant-skipper butterfly emerges to partake of Yucca filamentosa’s generous nectar. And so the cycle continues.

Habitats are characterized by openness, from coastal dunes to grasslands, open woodlands, and open yucca flats. Yucca giant skippers also are found around desert canyons.

Wingspan measures 1-7/8 to 3-1/8 inches (4/8 to 7.9 centimeters).

Yucca giant skippers have long and pointed forewings. Their black upperside is splashed with yellow bands near the lower outer margins of their forewings and the outer margin of their hindwings. Small white spots embellish the tips of the forewings. Orange-yellow to yellow spots sometimes are present on the hindwings of females. The grey undersides of hindwings are spotted with white.

Yucca giant skipper butterflies are born without functional mouthparts. Emerging between February and May, at most their flight plans traverse two months. The only known consumption of nutrients by Yucca giant skippers occurs in males as they sip up moisture from mud puddles.

Yucca giant skipper males exhibit an exuberant delight in the freedom of flight. As these connoisseurs of fast flight whisk powerfully and swiftly to their destinations, a whizzing sound is clearly audible from the friction of their wings speedily flapping through the air.

In the background, in the foreground, ever present from cradle to the grave, Adam's needle stands sentinel for Yucca giant skippers, ephemeral, enchanting expressions of metamorphosis in nature.

Megathymus cofaqui is commonly known as Cofaqui giant skipper butterfly.

Cofaqui giant skippers have claimed Florida as their paradise. Two isolated populations --- one in the panhandle, the other on the peninsula --- hail from the sunshine state.

Cofaqui giant skippers preferentially inhabit coastal dunes, pinewoods, and shrublands.

As with Yucca giant skippers, these skippers live out their various life stages on Adam’s needle as one of their favored host plants.

Wingspan measures 1-15/16 to 2-7/16 inches (5 to 6.3 centimeters).

Cofaqui giant skippers have relatively short and blunt forewings. Their black upperside is cheerfully arched with a broad yellow band on each forewing. Hindwings have grey undersides dotted with small white spots.

As with Yucca giant skippers, these skippers also lack functional mouthparts and live for, at most, a few months.

The fast-paced life of a Cofaqui giant skipper is closely and clearly defined ecologically. Their ecosystem, which is their biological environment, primarily is restricted geographically to the sunny state of Florida, although they have been reported in Georgia and as far north as North Carolina. Their synecology (Greek: σύν, syn, “with” + oικoλoγία, ecologia, “house” + “study”), which is their interaction with persistent cohabitants of their habitat, exhibits lifelong coexistence with their host plant. In sum, Cofaqui giant skippers discovered their paradise in the mists of time and have never evinced any disenchantment with Florida nor with Adam’s needle plants.

Tegeticula yuccasella is commonly known as the Yucca moth.

Wingspan measures about 1 inch (25.4 millimeters).

Forewings are usually white to creamy white, with rare tan coloration. The underside of forewings often are a surprising dark brown. Hindwings are generally white or very light grey. White hair-like fringes edge forewings and hindwings.

Eggs, which are delicate and thread-like, average 0.059 inches (1.5 millimeters) in length and less than 0.00393 inches (0.1 millimeters) in diameter. Newly hatched larvae measure less than 0.039 inches (1 millimeter) and reach 0.55 inches (14 millimeters) at maturity.

Larvae change from larval translucent whiteness to yellow of youth and red shades of maturity.

The entirety of the life stages of Yucca moths transpires solely around Yucca plants. In the eastern United States, during the daylight, Yucca moths are virtually transfixed by the creamy blossoms of Yucca filamentosa. The petite, delicate moths patiently position themselves on the inside of the petals, near the protective array of the stigma, the part where pollen is received and germinated, and the pistil (Latin: pistillum, "pestle"), the part where ovules mature into seeds. The evening fragrance and the beaming moon alert Yucca moths to the prime hours, between sunset and midnight, for oviposition (Latin: ovum, "egg" + ponere, "to put, to place"), that is, egg laying, and for pollination.

Female Yucca moths to Adam's needle: "I will find you":

Female Yucca moths are known to take to flight in the time before dusk. They visit newly opened flowers on Adam's needle plants in a locality. Apparently, females reconnoiter a wide area. Drawn by sensitivity to the flowers' fragrance, female Yucca moths locate Yucca filamentosa communities which are isolated and distant from the immediate area.

"I have often been struck with the power which the moth has of detecting isolated plants blooming for the first time remote from other plants or in localities where she could not possibly have been previously developed, a fact which indicates that, where abundant, in addition to her ordinary more sedentary duties, she takes long reconnoitering flights. . . ." (Charles Valentine Riley, p. 122)

As Yucca filamentosa is not self-pollinating and thus depends upon Yucca moths for preservation through pollination, the diligence exhibited by female Yucca moths in leaving no Yucca filamentosa flower unpollinated is extraordinary. In fact, Yucca moth females' brief lifespan of around two to five days is devoted exclusively to the preservation of two species, their own and Adam's needle.

Pollen, produced by the anthers, is removed by female Yucca moths. The pollen scrapings are rolled tightly into a ball. Triple the size of the females’ own heads, these balls often comprise nearly 10,000 grains of pollen at 10 percent of the moth’s weight. With pollen balls tucked between their heads and thoraxes and hugged by their tentacles, females visit different Adam’s needle flowers to drop the pollen ball into the pistil’s stigma and deposit their eggs inside the pistil.

When the eggs hatch, the plant's seeds, formed from the ovules, beckon them. Of 130 to 150 seeds, the larva usually requires less than two dozen and thus consumes that amount and no more. The remaining seeds represent an adequate amount to assure successful propagation through wind dispersal.

In its introduction outside of the New World to places without Yucca moths, Yucca filamentosa perpetuates itself by sprouting new plants through its roots. It is an effective method of propagation but the plant's distribution range is seriously compromised.

Without Yucca moths, Adam's needle plants do not experience pollination, do not produce seeds. Without Yucca filamentosa, Yucca moth larvae die. Yucca moths are the sole pollinators of Yucca filamentosa. In turn, Adam's needle seeds are the only food source of Yucca moth larvae. This mutually beneficial, inextricably interdependent interrelationship is known as obligate (Latin: obligare, "to bind") mutualism. In this symbiotic (Greek: σύν, syn, "with" + βίωσις, biosis, "living") relationship between two different biological species, both symbionts, or participants, have something to lose and something to gain.

The win-win relationship which Yucca filamentosa and Tegeticula yuccasella have established models an enticing section of the jigsaw puzzle of nature. These two species absolutely and incontrovertibly mesh. This fact begs the questions: Which came first, the moth or the flower? How did they realize that they were made for one another? Happenstance or evidence of a grand design?

Whatever the answers, whatever the perspective, the attractive, positive interrelationship between Yucca moths and Adam's needles was established prehistorically and has persisted to the present.

Adam's needle is a spectacular plant during florescence with its two-color harmony of creamy flower bells nodding above lush grey green to blue green foliage. Its height, with the dramatic showy flowers atop their spire and fountains of basal leaves above the ground, exemplifies the visual interests of landscape architecture. Adam's needle plants clearly enhance private and public lawns and gardens, where they understandably are popular constituents.

In addition, Adam's needle plants do not stand alone. They coexist with winged creatures which specifically and even exclusively seek them out. Black-chinned hummingbirds and broad-tailed hummingbirds specifically, but not exclusively, choose to alight on Yucca filamentosa, for yuccas, although desirable, are not their sole providers of nectar. Yucca and Cofaqui giant skippers inevitably pass through their stages of life with nourishment from Yucca filamentosa, in addition to other yucca species. Most significantly, Yucca moths display complete, unwavering fidelity to Adam's needle plants, which serve as their exclusive host plants.

Wherever Yucca filamentosa finds itself, its coterie finds it.

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

August 1809 drawing of two plants gifted by François Michaux (1770-1855) to Jardin de Trianon: PJ Redouté, Les Liliacées (1809), Vol 5, Plate 277: Public Domain, via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/300314

Yucca filamentosa, naturalized: Sten Porse, CC BY-SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Yucca-filamentosa-naturalised.JPG

YUFI Yucca filamentosa L. Adam's needle: USDA Natural Resources Conservation Service, Public Domain, via USDA PLANTS Database @ http://plants.usda.gov/core/profile?symbol=YUFI&mapType;=nativity

Smith College Gardens and Greenhouses, Northampton, central western Massachusetts: Rusty Clark ~ 100K Photos, CC BY 2.0, via Flickr @ http://www.flickr.com/photos/23206546@N04/6185893898/

closeup of Yucca filamentosa buds; Brookside Gardens, Wheaton Regional Park, Montgomery County, Capital Region, Maryland: David J. Stang, CC BY SA 4.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Yucca_filamentosa_17zz.jpg

Yucca filamentosa in June: Maja Dumat, CC BY 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Yucca_filamentosa_flower_1.jpg

Yucca filamentosa in home garden: Manu (lilli2de), CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/seven_of9/7528555968/

Yucca filamentosa at Monticello: kafka4prez, CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/kafka4prez/60979940/

Moab, eastern Utah: Mdf, CC BY-SA 3.0, via Wikimedia Commons @ https://fr.wikipedia.org/wiki/Fichier:Archilochus-alexandri-003.jpg

Black-chinned Hummingbird Chicks: Caitlin Ceci/Zion National Park (Zion NPS), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/zionnps/5205494274/

illustration by William Swainson (October 8, 1789 – December 6, 1855): W. Swainson, A Selection of the Birds of Brazil and Mexico (1841), Plate 74, Public Domain, via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/33812700

illustration by entomologist-artist Charles Valentine Riley (1843 - 1895): G.H. French, Butterflies of Eastern United States (1886), p.381, Public Domain, via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/980275

c. 1820 drawing by American entomologist-ornithologist John Abbot (1751-c.1840/1841): J.A. Boisduval, Histoire générale (1833), Plate 70, opp. p. 212, Not in copyright, via Internet Archive @ https://archive.org/stream/histoiregnra00bois#page/n30/mode/1up

Aegiale cofaqui: previous synonym of Megathymus cofaqui: H. Strecker, Lepidoptera (1872), Plate XV, Fig 2, opp. p. 135, Not in copyright, via Internet Archive @ https://archive.org/details/lepidopterarhopa00stre/page/n171/mode/1up?view=theater

"A Tegeticula moth is depositing a pollen ball onto a stigma of a Yucca plant.": Sherwin Carlquist, CC BY-SA 3.0, via Wikimedia Commons @ http://commons.wikimedia.org/wiki/File:Tegeticula.jpg

North Carolina Museum of Natural Sciences, Raleigh, northeast central North Carolina: Ryan Somma, CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/ideonexus/2420181232/

Yucca filamentosa L. - Adam's needle YUFI: Steve Hurst/Agricultural Research Service (ARS) Systematic Botany/Mycology Laboratory, Public Domain, via USDA-NRCS PLANTS Database @ https://plants.sc.egov.usda.gov/ImageLibrary/original/yufi_003_php.jpg

Osceola County, central Florida: sdbeazley, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/sdbeazley/5839764652/

Yucca filamentosa: Carl E. Lewis, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/carllewis/1219537696/

A quintet of pleasing flowers recommended by John Parkinson includes Yucca: John Parkinson, Paradisi in Sole Paradisus Terrestris, p. 435, Public Domain, via Internet Archive @ https://archive.org/details/paradisiinsolepa00parkrich/page/435/mode/1up

Cambridge University Botanic Garden: Magnus Manske, CC BY-SA 2.5, via Wikimedia Commons@ https://commons.wikimedia.org/wiki/File:Yucca_filamentosa_%27Adam%27s_Needle%27_(Agavaceae)_flowers.JPG

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• Available via USDA Natural Resources Conservation Service Fact Sheets and Plant Guides at: http://plants.usda.gov/java/factSheet

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• Available via Biodiversity Heritage Library at:  http://www.biodiversitylibrary.org/item/15206

Moerman, Daniel E. Native American Ethnobotany. Portland OR: Timber Press, 1998.

Moerman, Daniel. Native American Medicinal Plants: An Ethnobotanical Dictionary. Portland OR: Timber Press, 2009.

Moisset, Beatriz. “Yucca Moths (Tegeticula sp.).” Celebrating Wildflowers > Pollinators > Pollinator of the Month. U.S. Forest Service. Web. www.fs.fed.us

• Available at:  http://www.fs.fed.us/wildflowers/pollinators/pollinator-of-themonth/yucca_moths.shtml

Ortho's All About Attracting Hummingbirds and Butterflies. Des Moines IA: Meredith Books, 2001.

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• Available via Internet Archive:  https://archive.org/details/paradisiinsolepa00parkrich

Rau, Phil. “The Yucca Plant, Yucca filamentosa, and the Yucca Moth, Tegeticula (Pronuba) yuccasella Riley: An Ecologico-Behavior Study.” Annals of the Missouri Botanical Garden, Vol. 32, No. 4 (November 1945): 373-394.

Redouté, Pierre Joseph. Les Liliacées. Tome cinquième. Paris: L'Imprimerie de Didot Jeune, 1809.

• Available via Biodiversity Heritage Library at: https://www.biodiversitylibrary.org/page/300094
• Available via Internet Archive at:  http://archive.org/details/mobot31753002806708

Riley, Charles V. "The Yucca Moth and Yucca Pollination." Popular Science Monthly, Vol. XLI (June 1892): 171-182. Also in: Missouri Botanical Garden Third Annual Report (1892): 99-158.

• Available via Biodiversity Heritage Library at:  http://biodiversitylibrary.org/page/675320

Roth, Sally. Attracting Butterflies & Hummingbirds to Your Backyard. Rodale Organic Gardening Book. Emmaus PA: Rodale, 2001.

Skinner, Henry. "Pupal Differences in Megathymus (Lep.)." Entomological News, Vol. xxviii, No. 5 (May 1917): 232.

Strecker, Herman. "Description of a New Species of Aegiale and Notes on Some Other Species of North American Lepidoptera." Proceedings of the Academy of Natural Sciences of Philadelphia, Vol. XXVIII (1876):  148-153.

• Available via Internet Archive at:  https://archive.org/details/proceedingsofaca28acad

Strecker, Herman. Lepidoptera Rhopaloceres and Heteroceres, Indigenous and Exotic, with Descriptions and Colored Illustrations. Reading, PA: Owen’s Steam Book & Job Printing Office, 1872.

• Available via Biodiversity Heritage Library at: https://www.biodiversitylibrary.org/item/40156
• Available via Internet Archive at:  http://archive.org/details/lepidopterarhopa00stre

Swainson, William. A Selection of the Birds of Brazil and Mexico. London: Henry G. Bohn, 1841.

• Available via Biodiversity Heritage Library at:  http://biodiversitylibrary.org/bibliography/49941#/summary

“The Yucca Cactus and Yucca Moth: A Perfect Example of Co-Evolution.” National Biological Information Infrastructure > Ecological Topics: Pollinators. U.S. Geological Survey Biological Informatics Program. Web. www.nbii.gov

• Available at: http://www.nbii.gov/portal/server.pt/community/butterflies_and_moths/856/yucca_moths/4933

Trelease, William. "Notes and Observations. 1. Detail Illustrations of Yucca." Missouri Botanical Garden Third Annual Report (1892): 159-166.

• Available via Biodiversity Heritage Library at:  http://biodiversitylibrary.org/page/675521

Witthoft, John. “The Cherokee green corn medicine and the green corn festival.” Journal of Washington Academy of Sciences, Vol. 36 (July 1946): 213-219.

"Yucca Giant-Skipper Megathymus yuccae (Boisduval & Leconte, [1837])." Butterflies and Moths of North America. Butterfly and Moth Information Network, Kelly Lotts and Thomas Naberhaus. Web. www.butterfliesandmoths.org 

• Available at:  http://www.butterfliesandmoths.org/species/Megathymus-yuccae