Today’s
Ramble was led by Linda Chafin.
Here’s
the link to Don’s Facebook
album for today’s Ramble. (All the photos in this post are compliments of Don.)
Today’s
post was written by Linda Chafin and Dale Hoyt.
Today’s Focus: Butterflies and flowers in the International Garden
and Flower Garden.
24
Ramblers met today.
Announcements:
1)
Emily reviewed
the Congaree National Park trip that a few ramblers are going to make on Nov. 9
– 11 this fall. The details are on the Announcements
page of our website. The short version is: make your own reservations and
arrangements.
2)
Emily also
offered suggestions for when there are a large number of people attending our
weekly rambles. When the group is large it is difficult for everyone to hear
what the leaders are saying. This is made more difficult by the varied social
conversations that the group breaks up into. If you can’t hear and want to,
feel free to force your way closer to the leader and/or “shush” those around
you that are speaking. Those engaged in conversation should keep their voices
down and step away from the leaders to leave space for those who want to listen.
Please don’t be offended if you’re shushed.
Today’s reading: Bob Ambrose recited Trust, by Susan Kinsolving.
Show and Tell:
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| Southern Flannel Moth caterpillar |
Jeff
brought in a Southern Flannel Moth caterpillar, one of the most venomous
caterpillars in the U.S. – it is thickly coated with a “comb-over” of fur-like bristles
that range in color from tan to orange. Hidden among the “fur” are stiff
stinging spines that have venom glands at the base. Jeff read this account of
the effect of the stings: “The sting produces an immediate intense burning pain
followed by the appearance of a red grid-like pattern on the skin that matches
the pattern of the venomous spines on the caterpillar. Swelling and sometimes
also lymphadenopathy follow. In addition to the characteristic localized
symptoms, more general systemic manifestations may also occur including
headache, fever, nausea, vomiting, tachycardia, low blood pressure, seizures
and more rarely, abdominal pain, muscle spasms, and convulsions.” [source: http://entnemdept.ufl.edu/creatures/misc/moths/puss.htm] Clearly NOT a fellow to mess with!
Richard
brought several native grasses for Linda to identify: Big-top Lovegrass, Greasy
Grass, Yellow Foxtail Grass, and Gama Grass (one of the grasses that is thought
to be an ancestor of modern corn or maize). There will be more in-depth
discussion of grasses as we move into fall and visit the powerline prairie.
Today’s route: From the Visitor Center we walked through the
International Garden and to the lower level of the Flower Garden, pausing where
ever we found butterflies or interesting flowers.
Visitor Center Plaza:
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| Two color forms (“morphs”) of the Eastern Tiger Swallowtail The dark tiger stripes are visible on the melanistic (dark) form Both are nectaring on Mexican Sunflower. |
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American South Garden:
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| Sweet Pepperbush |
Coastal Plain Sweet Pepperbush is a common shrub of the
southeastern Coastal Plain, usually occurring in swamp forests and around the
edges of other wetlands where its flowers are very attractive to both native
bees and European honey bees. Like many wetland species, it will also thrive in
upland gardens if watered. It spreads by both seeds and underground stems
(rhizomes). The “pepper” part of the name refers to the resemblance of its
dried fruits to black peppercorns.
Late summer and early fall is the time when plants in the composite
(or aster) family really come into their own. Today we saw several species in
this family:
Eared Coneflower is one of the
rarest plants in Georgia, occurring only in two southwestern Georgia counties.
Found naturally along creeks and in seepy wetlands, it will also thrive in
upland gardens, where it can reach a height of 10 feet or more. The large cone
in the center of the flower head is covered with tiny, dark brown disk flowers,
a give-away that this species is actually one of the Black-eyed Susans (genus Rudbeckia), in a different genus altogether
from Purple Coneflower (genus Echinacea).
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| Elephant’s Foot |
Elephant’s Foot is also in the
composite family, but you would be readily forgiven for doubting that. There
are no ray flowers (“petals”) surrounding a central disk or cone, an
arrangement that is the hallmark of the composite family. Instead, Elephant’s
Foot has only a few pink disk flowers, each deeply divided into five narrow
segments. Beneath the disk flowers are three conspicuous, oval, dark green
bracts (bracts are leaf-like structures associated with flowers). The stem is
leafless but at ground level several large, blunt-tipped leaves are pressed
flat against the ground. If you see a similar plant with leafy stems, it is a
close relative called Leafy Elephant’s Foot (Elephantopus carolinianus).
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| Joe Pye Weed visited by Fiery Skipper |
Joe Pye Weed is one of the
showiest of the species in the composite family. It’s native to most of the
U.S. east of the Mississippi, including north Georgia. Pollinator-gardeners
love this plant–its huge pinkish-lavender inflorescences attract dozens of
different insect species. Like Elephant’s Foot, its flower heads lack ray
flowers and consist of only 5-7 disk flowers. However, each plant may have
hundreds of florets that provide both nectar and pollen to insect visitors.
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| Mexican Sunflower visited by Long-tailed Skipper |
Mexican Sunflower is also popular
with butterflies. Native to Central and South America, this species has the
classic composite head, with a whorl of orange ray flowers surrounding a center
of small, orange disk flowers, where nectar is produced, as this foraging Long-tailed Skipper
demonstrates. Not a true sunflower (which would be genus Helianthus), this plant is sometimes called Tree Marigold, but it’s
not a marigold either!
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| Orbweaver spider (Neoscona sp.) |
We captured an Orbweaver spider near a large web, possibly the one that had done the weaving.
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| Carolina Phlox |
Carolina Phlox is one of a few
summer-flowering phlox species in our area (most flower in the spring). It’s a
great garden plant: likes dry soils and full sun but will also thrive in
moister, somewhat shadier areas. It attracts pollinators whose mouthparts are
long enough to reach the base of the flower tube, such as butterflies,
skippers, moths.
Spanish America Section:
Tibouchina is a
genus of the American tropics, hence not a Georgia native. However, the
Meadow-beauty family, of which it is a member, is well represented in our state
by 12 species of meadow-beauties, all in the genus Rhexia, and all very pretty in flower. While the four colorful petals and the persistent, urn-like
fruits are reason enough to love this genus, what really fascinates me are the
eight “hinged” stamens. Each deeply curved anther (the part of the stamen where
the pollen is produced) is loosely attached to the top of the filament (the
stalk part of the stamen)–the anther rocks back and forth if you touch it–and
provides what seems to be a precarious “handhold” to the bumblebees that visit
the flowers for pollen. (There is no nectar.) The pollen emerges only from a
pore at the tip of the anther by way of buzz pollination. When a bumblebee
grabs hold of the anther, it vibrates its thoracic muscles, which vibrates the
anther, and shakes the pollen out through the pore. Although none are planted
at the Garden, Maryland Meadow-beauty (Rhexia
mariana) is common throughout Georgia and occurs in Athens around ponds and
in wet ditches, where it flowers from mid-summer through early fall.
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| Maryland Meadow Beauty |
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| Tibouchina with stamen parts identified. Compare the anthers with those of the Meadow Beauty above. |
Two native
species in the mint family that we saw today, Spotted Bee-balm and Southern Mountain-mint,
are in peak flower and attracting a variety of pollinators.
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| Spider Wasp nectaring on Spotted Bee-balm |
Here,
Spotted Bee-balm, with its showy pink bracts and spotted yellow flowers, has
attracted the attention of a Spider Wasp.
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| A Carpenter Bee visits a Southern Mountain Mint |
Purple Salvia is a South American
member of the mint family, and exhibits four defining characteristics of that
family: square stems, opposite leaves,
strongly smelling leaves, and tubular flowers with two flaring lips at the top.
The flowers are too narrow to allow Carpenter Bees to enter in search of nectar.
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| Carpenter Bee robbing nectar from Salvia blossom |
Instead, these large bees use their chewing mouthparts to make a hole through
the calyx and into the base of the flower where the nectar is. Although we
humans refer to this practice pejoratively as nectar-robbing, studies have
shown that the plants’ reproductive success doesn’t seem to suffer from this
“thievery.”
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| Tiny metallic-colored bee on Salvia |
This wonderful close-up photo by Don of a green metallic bee visiting
the flower also shows the tiny, ball-tipped glands that cover the flower of Purple
Salvia. Each of these glands exudes essential oils that are responsible for the
strong smell we associate with salvias.
Mediterranean and Middle East Section:
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| The fruit of Jumson Weed is known as a “Thorn Apple” |
The large, white, fragrant
flowers of Jimson Weed are gone now and have been replaced by spiny, green developing
fruits. The fruit will eventually turn brown, split into four sections, and
release its large, brown, highly toxic and hallucinogenic seeds (20 seeds from
one fruit can kill a child).
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| Melanistic Eastern Tiger Swallowtail nectaring on Lantana The crescent-shaped marks on the hind wings indicate that this is a female; females can be either yellow and black or melanistic; males are nver melanistic. The melanistic females are thought to mimic Pipevine Swallowtails (see text). |
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| Giant Swallowtail nectaring on Lantana |
Lantana and Butterfly-bush are
both in full flower and today are living up to their reputation as butterfly
magnets–we saw many Eastern Tiger Swallowtails, Giant Swallowtails, Gulf
Fritillaries, and Fiery Skippers visiting their flowers.
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| Gulf Fritillary nectaring on Butterfly bush |
Both of these plants are
exotics–Lantana is from Central and South America, and Butterfly-bush hails
from China–and both are known to establish in natural areas. Lantana is listed
by the Georgia Exotic Pest Plant Council as “Category 3: Exotic plant that is a
minor problem in Georgia natural areas, or is not yet known to be a problem in
Georgia but is known to be a problem in adjacent states.” Butterfly-bush is
invasive in the Pacific Northwest and Mid-Atlantic states, but not yet
considered a problem in Georgia.
Chaste Tree is in fruit now, and
Susie shared a great story on the origin of the common name: also known as monk’s-pepper, the fruits were
thought to suppress libido, rendering Medieval monks chaste. However, Southern
Living writer Steve Bender reports that “wearing a house dress with orthopedic
shoes and multiple nose piercings is much more effective” than Chaste Tree
fruits for curbing a monk’s libido (https://www.southernliving.com/garden/grumpy-gardener/chaste-tree-is-pure-delight).
Herb and Physic Garden:
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| Obscure Bird Grasshopper found on Mountain Mint |
Today’s Butterflies: There has been a literal explosion of many
butterflies in the last week or so. Ed and Sue alerted us to the abundant Tiger
Swallowtails, as well as another species, at various locations in the garden.
It was true, for we saw more than a dozen Tiger Swallowtails, plus at least one
Pipevine Swallowtail, one or two Giant Swallowtails and a Black Swallowtail.
Questions about today’s butterflies:
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| Scales from Eastern Tiger Swallowtail clinging to my finger after handling a yellow and black male butterfly. Note that each scale is a single color, either black or yellow, and roughly rectangular in shape. |
Why does a butterfly have scales on its
wings? The upper and lower wing
surfaces in most butterflies and moths are covered with microscopic scales.
Each scale is shaped like a rectangle and attached by one of its narrow ends to
the wing. The scales are arranged like shingles on a roof and each scale has a
single color, but there can be many different scale colors. The color pattern
arises like a pointillist painting, each scale contributing a single point of
color.
The
color pattern on the wings is species-specific and enables butterflies to find
an appropriate mate.
The
scales are easily removed, a feature that makes butterflies and moths harder
for spiders to catch in their webs. The moth that blunders into a spider web
may leave behind many scales stuck to the sticky strands, but it can escape
with its life. The wings look slightly more worn.
Can a butterfly fly if it loses its
scales? The butterfly wing is more
than the scales attached to it. It is part of the tough exoskeleton of the
insect and can function perfectly well even if it has lost all of its scales. As
a butterfly ages it gradually loses its wing scales. Such old butterflies look
as if their color pattern has faded.
Why are some Tiger Swallowtails black
while others have the yellow and black “tiger” pattern? The dark, melanistic,
form of the Tiger Swallowtail is only found in females. All the males sport the
yellow and black tiger pattern, while females can be either melanic or yellow
and black. The black coloration is controlled by a single gene that is
expressed only in females. Males can carry this gene, but it will not be
expressed. The number of melanistic females in a population varies from zero to
> 75%. The gene for melanism is commonest in areas where another dark-colored
butterfly, the Pipevine Swallowtail, is also common. In areas where the
Pipevine Swallowtail is less common there are fewer melanistic Tiger
Swallowtails.
How does the presence of Pipevine
Swallowtails affect how common melanistic Tiger Swallowtails are? Melanistic Tiger Swallowtails are thought to be Batesian mimics of the Pipevine
Swallowtail. Pipevine Swallowtail caterpillars feed on plants in the Pipevine
family, Aristolochiaceae. These plants contain a very toxic substance,
aristolochic acid, that the Pipevine caterpillar stores in its body. The toxic
substance is transferred to the adult butterfly during metamorphosis, making
the adult butterfly both distasteful and toxic. (This is like the Monarch
butterfly, but the toxic material is different.) A single attempt to eat a
Pipevine Swallowtail butterfly is enough to keep a bird from eating another one,
or a butterfly that resembles it.
This
kind of mimicry, in which an edible or harmless species resembles a toxic, distasteful
or harmful (e.g., stinging) species, is called Batesian mimicry, named after
the English naturalist Henry Walter Bates who discovered it.
In
areas where Pipevine Swallowtails are
abundant the melanistic Tiger Swallowtails are “protected” from bird attacks
because they are mistaken for Pipevine Swallowtails.
Why don’t all the female Tiger
Swallowtails become melanistic?
Because male Tiger Swallowtails seem to prefer to mate with the yellow and
black females. (This was determined by counting the number of sperm packages in
the female reproductive tract. The yellow and black females contain more sperm
packages than melanistic females.) If male mating preference were the only
factor, the melanistic form would eventually disappear. This is seen in the
northern areas of the United States and Canada where there are no Pipevine
Swallowtails. There the females are all yellow and black. But, as you move
further south, in areas where Pipevine Swallowtails live, the melanistic form
becomes more common. This suggests that the darker female picks up a survival
advantage that compensates for her lower frequency of mating.
Why don’t other butterflies mimic the
Pipevine Swallowtail? The short
answer is that they do! In the southern US there is a mimicry complex in which
several species of butterflies, including non-swallowtails, mimic the Pipevine
Swallowtail.
What does it take to mimic the Pipevine
Swallowtail? Viewed from above, the
PVST is black with metallic blue hind wings. The actual color of the hind wings
depends on your viewing angle. The color is structural, rather than due to a
pigment. From some angles the hind wings will appear metallic green; from others,
they are blue and, from still others, black. Metallic bluish green is probably
the best description.
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| Pipevine Swallowtail; the metallic blue color is structural, not a pigment, and will vary from blue to green to black, depending on the angle of view. By Renee from Las Vegas, USA (Pipevine Swallowtail) [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons |
The
proposed mimics of the Pipevine Swallowtail are:
1)
Eastern Tiger
Swallowtail melanistic female; black above with blue crescents on the margin of
the hind wings. (See photos elsewhere in this post.)
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| Black Swallowtail female
Kenneth Dwain Harrelson [GFDL |
2)
Black Swallowtail
female; mostly black above with blue crescents on the margin of the hind wings.
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| Spicebush Swallowtail female
By Meganmccarty [Public domain], from Wikimedia |
3)
Spicebush
Swallowtail; dark above, hind wings with greenish (male) or bluish (female)
color.
4)
Diana
Fritillary; female dark above, hind wings with blue border. (male is completely
different: orange and brown)
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| Red-spotted Purple
By Jacob Abel (Bugguide.net) [Public domain], via |
5)
Red-spotted
Purple; both sexes dark above and with blue border on hind wings.
The
Batersian mimicry hypothesis has been tested with some of the above species. Florida
Scrub Jays that had never seen a Pipevine Swallowtail attacked and swallowed
the first one offered. They immediately
retched and regurgitated the butterflies. When subsequently offered the melanistic
female tiger swallowtails, spicebush swallowtails or black swallowtails, they
declined to eat them. Other captive birds that had, presumably, already
experienced pipevine swallowtails prior to being captured, also did not eat the
offered species.
SUMMARY
OF OBSERVED SPECIES
|
Eastern |
Papilio |
|
Mexican |
Tithonia |
|
Sweet |
Clethra |
|
Tachinid |
Family |
|
Cut-leaf |
Rudbeckia |
|
Elephant’s |
Elephantopus |
|
Orbweaver |
Neoscona |
|
Goldenrod |
Solidago |
|
Carolina |
Phlox |
|
Eared Giant Black-eyed Susan |
Rudbeckia |
|
Tibouchina |
Tibouchina |
|
Purple |
Salvia |
|
Carpenter |
Xylocopa |
|
Jimson |
Datura |
|
Beautyberry |
Callicarpa |
|
Lantana |
Lantana |
|
Butterfly |
Buddleia |
|
Gulf |
Agraulis |
|
Scoliid |
Scolia |
|
Chaste |
Vitex |
|
Joe |
Eutrochium |
|
Giant |
Papilio |
|
Fiery |
Hylephila |
|
Silver |
Epargyreus |
|
Bumblebee |
Bombus |
|
Asian |
Ulmus |
|
Mountain |
Pycnanthemum |
|
Obscure |
Schistocerca |
|
Spotted |
Monarda |
|
Spider |
Family |