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The yucca moth, also commonly called the pronuba moth, is a small white moth
that lives in the semi-arid habitats where yucca plants grow. The yucca moth
is well-known for its co-dependant relationship with the yucca plant. The yucca
moth’s larvae rely exclusively on the seeds of the yucca plant as a primary
food source, and the plant relies exclusively on the yucca moth for pollination.
One cannot exist without the other, creating an obligate mutualism between the
moth and the plant. This is true of two out of the three genera of yucca moths,
the Tegeticula and Parategeticula.
Range
Conforms to its yucca plant species host's range (which may vary from region
to region). The yucca moth is native to the southwestern United States and Mexico.
The Sonoran Desert region is home to approximately ten species of yucca plant,
and where there are yucca plants, there are yucca moths. Yucca moths are also
found in the southeastern portion of the U.S. and the West Indies, where just
one species of yucca plant is known to exist.
Taxonomy
Belongs to the order of Lepidoptera, insects with four wings covered
with minute scales; order includes moths, butterflies and skippers.
There are approximately 80 species of Prodoxidae.
Class -- Insecta
Superorder -- Amphiesmenoptera
Order -- Lepidoptera
Suborder -- Glossata
Infraorder -- Heteroneura
Superfamily -- Incurvarioidea
Family -- Prodoxidae
Overall Anatomy
The yucca moth is silvery, white and small in size.
In the course of its evolution, the Yucca Moth has developed specialized mouth
organs that it uses to collect the yucca's pollen, packing and transporting the
tacky substance under its head (or "chin").
- body length of roughly less than an inch
- wing span of about an inch
- females are slightly larger than males
- whitish forewings with white hair-like fringes in most species, some with
dark markings; dark wing color in some species
- grayish brown hindwings with white hair-like fringes
- white head and thorax (the body's second, or midsection);
- brownish abdomen (the body's third section)
- yellowish legs
- antennae
Behavior
In the spring, the yucca moths emerge from their subterranean cocoons and
are lured by the fragrance of the blooms on the nearby yucca plants. The yucca
moths spend most of their time perched on or near yucca plants. If the moths
are not resting, they are flying from plant to plant, collecting pollen, pollinating,
mating or laying eggs.
If you want to observe a yucca moth in action, find a yucca plant in bloom.
The yucca moth usually rests on the yucca plant or bloom during the day and pollinates
and lays eggs at night when the blooms are fully open.
Reproduction and Life Cycle of the Yucca Moth
Male and female Tegeticula yuccasella moths use the yucca blooms as a bridal
chamber, with the male abdicating all responsibility for the female and the larvae
after mating. Mating occurs in the evening hours when the yucca blooms are fully
open.
When the yucca plant begins its spring bloom, signaling its readiness for
pollination, the yucca moth, using her specialized mouth organs, collects the
highly adhesive pollen from the yucca flowers' male sex organs, or anthers. Typically
secretive - the female yucca moth works only in the darkness between sunset
and midnight - and choosy - she seeks the newest of blooms - the
yucca moth, once pollen laden, now enters a flower and circles and evaluates
the female reproductive organ, or ovary. She may withdraw and renew her search
if she finds that another yucca moth has visited the flower ahead of her. Once
she makes a choice, she lays eggs in a specific location within the flower's
ovary. She then climbs the ovary's stigma and deposits a small fragment of her
pollen, fertilizing the flower so that it soon begins producing fruit and the
seeds for her coming offspring. With only a few days left in her lifetime, she
soon moves on, searching for another acceptable bloom.
The yucca moth’s larvae hatch within several days, with the yucca plant
- keeping its end of the bargain - providing its fruit for housing and some seed
for food. When conditions are right, ideally soon after a nighttime thunderstorm,
the yucca moth larvae leave the fruit of the yucca and drop to the desert soil.
They burrow down one to three inches. Each creates a cocoon, where it may develop
for several weeks to several years before it emerges to renew the cycle.
Interesting Facts About The Yucca Moth
- The female yucca moth collects pollen, forming a compact ball that is three
times the size of her head which she transports to other yucca flowers
- The yucca moth is one of the oldest moth species
- Yucca plants would not exist without the yucca moth and vice versa
The Yucca Moth and the Yucca Plant
Even though they belong to two different kingdoms in the universe of life
on our planet, the yucca moth species known as "Tegeticula yuccasella" and
the yucca plant species known, popularly, as the "soaptree yucca" and,
scientifically, as the "Yucca elata" have forged an inseparable bond.
They co-evolved over millions of years, and maintain a mutual dependence. Although
dozens of other yucca moth and yucca plant species have similar relationships,
the Tegeticula yuccasella and Yucca elata, in the United States' desert Southwest,
stand as a classic example of the biological phenomena known as "coevolution" and "mutualism."
 Watch
a video about the Joshua Tree (Yucca brevifolia).
In their biological partnership, the moth depends on the fruit of the yucca
for the developing seeds that serve as the sole source of food for its larvae.
Conversely, the yucca depends on the females of the moth species for the pollination
of its flowers and the consequent production of fruit and seeds. Without the
Yucca elata, the Tegeticula yuccasella would perish with the last of the existing
generation. Without the moth, the yucca would expire with the end of the existing
stands. (The yucca can sprout new plants from its roots, but it cannot readily
expand a range or establish new ranges to form new stands without the more mobile
seeds.)
Author: Jay Sharp
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