This web page contains three short essays written
by Allegheny faculty on the subject of mayflies, along with commentaries
and other material connected to the writing of these essays. The
first purpose of the page is to demonstrate how different disciplines
-- in this case Biology, Religious Studies and English -- think
and write about the same subject in different ways. Faculty involved
in shaping the central aims of FS201 have agreed that such disciplinary
differences should be a part of what the sophomore seminar has us
think about. As explorers in a liberal arts curriculum, Allegheny
students must continually negotiate the different conventions, assumptions
and methodologies that distinguish the work of one academic department
from another. As second-year students narrowing their sights on
a major, students in the sophomore seminar have a particular need
to see and understand these differences. We hope the essays and
connected material on this webpage help in that process.
And why mayflies? Here, our motivation is more arbitrary.
Richard Wilbur's wonderful poem on the subject first appeared last
year, prompting Ben Slote's interest in the subject, one which clearly
invites multi-disciplinary responses. Professors Mumme and Russell
were soon similarly interested. But we could have chosen nearly
any other subject. Indeed, the Associate Dean invites faculty in
other departments to write short essays for this webpage -- on the
happy subject of mayflies or any other subject they would like to
swarm around. (See the Associate Dean for remunerative details.)
-- Introduction by Ben Slote
The
Evolution of Synchronous Emergence in Mayflies
Ron Mumme
Department of Biology
Allegheny College
click here
to read Prof. Mumme's commentary on scientific writing
The synchronous mass emergence of mayflies -- insects
in the order Ephemeroptera -- is one of nature's most striking spectacles.
Gathering near water, newly emerged males often form huge mating
swarms and fly up and down in characteristic "dances" that serve
to attract females. After entering the swarm to mate, females deposit
their eggs in a neighboring stream or pond. The aquatic larvae may
take a year or more to develop, but in most of the world's 2,000
species of mayflies, the winged adults are unable to feed and rarely
live more than a few days. Because of their short adult lifespan
and highly synchronous pattern of emergence, the order Ephemeroptera
-- from the Greek ephemeros for short-lived and pteron
for wings -- is aptly named (Borror et al. 1976, Gilliot 1980, Rosenbauer
1999).
Why is adult emergence in mayflies so highly synchronous?
Two hypotheses have been proposed to explain the evolution of synchronous
emergence. Corbet (1964) suggested that synchronous emergence may
increase the probability of finding a mate. Under this hypothesis,
mayflies that emerge before or after the peak period of emergence
for their species may encounter difficulty locating mates during
their brief adult life. If so, early- and late-emerging mayflies
would produce relatively few offspring and natural selection would
favor adults that emerge synchronously.
Although Corbet's "mating success" hypothesis has
not been tested by direct comparison of mating success of synchronously
and non-synchronously emerging adults, Sweeney and Vannote (1982)
tested the hypothesis indirectly by analyzing emergence patterns
of obligately parthenogenetic (unisexual) mayflies. In these species,
males have never been recorded and females lay unfertilized eggs
that eventually develop into other females. Because natural selection
for improved mating success is clearly absent in these all-female
species, Corbet's mating success hypothesis predicts that obligately
parthenogenetic mayflies should emerge less synchronously than should
more typical bisexual species.
Sweeney and Vannote tested this prediction by examining
the emergence pattern of 16 species of mayflies found in White Clay
Creek in eastern Pennsylvania. Contrary to the prediction of the
mating success hypothesis, the emergence pattern of the three unisexual
species was no less synchronous -- and perhaps even slightly more
synchronous -- than the pattern for the 13 species of bisexual mayflies
(Sweeney and Vannote 1982). This indirect test therefore provided
no empirical support for the mating success hypothesis.
The second hypothesis for synchronous adult emergence
is the "predator satiation" hypothesis (Sweeney and Vannote 1982;
see also Williams et al. 1993). Under this hypothesis, synchronous
mass emergence may act to overwhelm the capacity of local predators
to consume adult mayflies. If so, individuals emerging synchronously
may experience a reduced per capita rate of predation relative
to individuals emerging before or after the period of peak emergence.
Thus, under the predator satiation hypothesis, natural selection
exerted by predators has led to the evolution of synchronous emergence
in mayflies.
Sweeney and Vannote (1982) tested the predator
satiation hypothesis by examining predation rates on emerging adults
of the mayfly Dolania americana, a species that is common
in the southeastern United States. Dolania americana has
a two-year life cycle with an absurdly brief adult stage that can
be measured in minutes. Eggs are laid in the waters of sandy-bottomed
streams in early June but do not hatch until the following April.
Larvae, which prey on the larvae of midges and other aquatic insects,
require 14 months to mature and metamorphose into winged adults.
During the brief period of emergence, mature larvae swim to the
stream surface at dawn and quickly molt into the winged adult form,
leaving the shed larval exuvia ("molt skin") floating on the surface.
Adult females typically live less than five minutes, just long enough
to locate a mate and release their fertilized eggs back into the
stream. Adult males live only slightly longer; after emergence,
males patrol above the surface of the stream, searching for and
mating with females until they are either eaten by an aerial predator
or, after about 30 minutes of adult life, fall into the water from
exhaustion and die (Sweeney and Vannote 1982).
Sweeney and Vannote studied adult emergence of Dolania
americana during 1980 along a 100-meter stretch of Upper Three
Runs, a small stream in Aiken County, South Carolina. Emergence
was highly synchronous and all adults in their study population
emerged May 31 - June 15, with peaks of emergence occurring June
4-5 and June 7-9. For seven mornings during the 16-day emergence
period, Sweeney and Vannote were able to determine both the number
of adults that emerged and the number that were killed by predators.
They obtained these data by spanning the creek with a series of
nets that captured both the shed larval exuvia of emerging mayflies
and the bodies of adults that died a "natural" death following mating
flights (males) or egg laying (females). The difference between
the number of larval exuvia and adult bodies captured each day provided
Sweeney and Vannote with an estimate of the number of adults that
succumbed to one of the many predators (several species of birds,
bats, dragonflies, spiders, and the whirligig beetle Dineutus
discolor) that readily ate emerging mayflies.
|
Fig. 1. Predation rate on adults of
the mayfly Dolania americana in relation to number
of adults emerging during seven days of the 1980 emergence
along Upper Three Runs, Aiken County, South Carolina. Lines
portray the best-fit regression line for males (red) and females
(blue). Modified from Sweeney and Vannote (1982).
|
For both males and females, Sweeney and Vannote
found an inverse relationship between the number of adults
emerging on a particular morning and the proportion taken
by predators (Fig. 1). In other words, the larger the number
of mayflies that emerged on a given morning, the less likely
it was that an individual mayfly was eaten by a predator.
The research of Sweeney and Vannote (1982) therefore provides
strong support for the predator satiation hypothesis and suggests
that synchronous emergence in mayflies is an adaptation that
reduces the individual risk of predation.
|
Literature Cited
Borror, D. J., D. M. DeLong, and C. A. Triplehorn.
1976. An Introduction to the Study
of
Insects (4th ed.). Holt, Reinhart and
Winston: New York.
Corbet, P. S. 1964. Temporal patterns of emergence
in aquatic insects. Canadian
Entomologist
96:264-279.
Gillott, C. 1980. Entomology. Plenum Press:
New York.
Rosenbauer, T. 1999. Streamborne beauties. Audubon
101(3):30-35.
Sweeney, B. W., and R. L. Vannote. 1982. Population
synchrony in mayflies: a predator
satiation
hypothesis. Evolution 36:810-821.
Williams, K.S., K.G. Smith, and F. M. Stephen. 1993.
Emergence of 13-yr periodical
cicadas
(Cicadidae: Magicicada): phenology, mortality, and predator satiation.
Ecology
74:1143-1152.
Wilbur's
"Mayflies" and the Call of Artifice
by Ben Slote
Allegheny College Meadville, PA 16335
click here
for Professor Slote's commentary about writing his essay on
Wilbur's "Mayflies."
|
click here
for a Microsoft Word version of Professor Slote's essay (all
formatting in the Microsoft Word version of the document conforms
to the MLA style)
|
Richard Wilbur's recent
poem "Mayflies" reminds us that the American Romantic tradition
that Robert Frost most famously brought into the 20th century has
made it safely into the 21st. Like many of Frost's short lyric poems,
"Mayflies" describes one person's encounter with an ordinary but
easily overlooked piece of nature -- in this case, a cloud of mayflies
spotted in a "sombre forest"(l.1) rising over "unseen pools"(l.2),
-- made surprisingly attractive and meaningful by the speaker's
special scrutiny of it. The ultimate attraction of Wilbur's mayflies
would appear to be the meaning he finds in them. This seems to be
an unremittingly positive poem, even as it glimpses the dark subjects
of human isolation and mortality, perhaps especially as it
glimpses these subjects. In this way the poem may recall that most
persistent criticism of Wilbur's work, that it is too optimistic,
too safe. The poet-critic Randall Jarrell, though an early admirer
of Wilbur, once wrote that "he obsessively sees, and shows, the
bright underside of every dark thing" -- something Frost was never
accused of (Jarrell 332). Yet, when we examine the poem closely,
and in particular the series of comparisons by which Wilbur elevates
his mayflies into the realm of beauty and truth, the poem concedes
something less "bright" or felicitous about what it finally calls
its "joyful . . . task" of poetic perception and representation
(l.23).
In this poem about seeing from
the shadows, the speaker's revelations are invariably ironic. What
could be a more unpromising object of poetic eloquence than mayflies,
those leggy, flimsy, short-lived bugs that one often finds floating
in the hulls of rowboats? Yet for Wilbur these insects, by the coordinated,
undulating flight of their teeming masses, become something beautiful,
"lifelong dancers of a day"(l. 17). More surprising yet, though
surely emblems of the ephemeral (of the order ephemeroptera),
they suggest by their choreographed life an interconnectivity in
nature that transcends an individual's mortality. Indeed, in the
third and final stanza they become a foil for the speaker's own
sense of "separateness" and mortality "as night close[s] in"(l.18).
At a literal level the poem all along insists on the speaker's separation,
as "witness"(l. 9), from this "manifold/ And figured scene"(ll.
13-14). To see the dance so well, he has had to be stationed outside
it. This exclusion, it would seem, is the poet's classic occupational
hazard.
Yet this darker revelation is quickly eclipsed by
one last happy irony, a revelation of sorts: the poem so artfully
represents its subject, its conspicuous ingenuities of form so undulate
and glitter like the mist of mayflies, that the poem itself becomes
the mayflies -- or means to come as close as language can take it.
As a special way of seeing, the poem means to breech the gulf between
seer and thing seen and thus forge a connection to the object world,
the speaker's own absence from which he ostensibly laments. That
this attempt is successful seems implicit in the last lines of the
poem. There, it occurs to the speaker that his sense of separateness
and mortality can be allayed by the idea that he has been "called"
to be a poetic seer, "one whose task is joyfully to see/ How fair
the fiats of the caller are"(ll.23-24). By poetically embracing
his "task" of seeing, the speaker can do the next best thing to
being part of nature's immortal, "glittering" (l.5) choreography;
he can connect it to us through an immortal poem, and then he and
we can "joyfully" celebrate the "fairness" -- the beauty and the
justice -- of his responsibility, just as we relish those other
imperious fiats that summon stars to the sky and mayflies to a "ragged
patch of glow"(l.4).
What troubles this happy
conclusion is the extent to which the poem seems to concede its
dependence on something other than, and very different from divine
or natural presentation, that is, human artifice. This admission
is clearest in the middle stanza, when the speaker's description
of the flies becomes most richly metaphorical:
It was no muddled swarm I witnessed, for
In entrechats each fluttering insect there
Rose
two steep yards in air,
Then slowly floated down to climb once more,
So that they all composed a manifold
And
figured scene,
And seemed the weavers of some cloth of gold,
Or the fine pistons of some bright machine. (ll.9-16)
This is no muddled swarm of
words. Exactly as in the first and third stanzas, pairs of pentameter
lines alternate with a short (trimeter), then shorter (dimeter)
line, with nearly every foot of the stanza iambic, catching the
regular, alternating rhythm of the rising and falling flies, and
the repeating rhyme scheme (abbacdcd) underscoring the graceful
symmetries of repetition. But next to this fly-inspired handiwork,
the sequence of comparisons that mark the progress of the stanza
seems muddled indeed. "Entrechats," those wonderful heel-clicking
leaps of dancers, evoke the "manifold/ And figured scene" of ballet,
with all the "fluttering" and "slowly floating down" of ballerinas.
The image carries the dancing motif begun in the first stanza where
the speaker compares the flies to a "crowd/ Of stars" (ll.5-6) participating
in the "great round-dance" of the constellations (l.8). As French
dance terminology, though, "entrechats" also marks a departure from
the natural world into a narrow realm of human culture, high culture
even. The next comparison -- the flies "seemed the weavers of some
cloth of gold"(l.15) -- makes further inroads in the organic vision
of the poem by quietly (but clearly) detaching the mayflies from
the beauty they produce. They are now not just there, being,
like stars the product of some natural or supernatural power (the
"caller" at the end), but are themselves agents of manufacture;
they don't "compose" (l.13) or constitute the scene, as did the
dancers, but are composers of it.
Dwelling on these shifts or inconsistencies might
seem to violate the spirit of the poem were it not for the last
metaphor of the stanza, which compares the flies to an archetype
of human invention, "the fine pistons of some bright machine" (l.16).
This image, like the others, is visually ingenious; it suggests
a simultaneous and perfectly timed integration of risings and fallings
that glisten as they churn. Yet while this comparison captures analogous
light and motion and part-to-whole relations, it is obviously, even
aggressively inappropriate in other ways: unlike flies, stars, ballet
dancers and cloths of gold, engines are utilitarian, their pistons
churning only in the service of human ends, to take people where
they want to go. The line's startling difference is accentuated
by its combined stresses -- "fine pistons
of some bright machine" -- which occur
nowhere else in the poem. The poem's work as a kind of pure, natural
witness seems completely suspended now. The only way Wilbur's "bright
machine" can stand for natural, impractical aesthetic beauty is
for us to see the machine itself analogously, as suddenly reminiscent
of, say, a beautiful mist of mayflies in the sun.
The poem admits its dependence
on artifice in the second stanza by admitting into its presentation
of the mayflies man-made constructions of increasing artificiality:
first highly stylized human dancers, then humans (weavers) who create
and are not themselves objects of beauty, then objects of strictly
human contrivance and human use (pistons). This admission is not
something a poem should make if it means to dramatize the poet's
"joyful" obligation of just seeing and means to suggest that
this act binds the poet to the natural world he represents. The
admission is not recanted, though. It seeps into the last stanza,
undermining what at first seemed like a wholly redemptive or even
triumphant ending. The speaker's sudden inference about his joyful
task of seeing, which interrupts his dark thoughts in the middle
of the stanza like a bright epiphany, is presented as strictly self-generated:
"Unless, I thought, I had been called to be/ Not fly or star . .
." Where does this possibility come from? If not out of nowhere
then only out of his own mind. And even he may not be so sure, since
the thought is governed by a term of speculation, "Unless," which
admits the possibility that he is wrong. In the very attempt to
surmount his separation from the natural world, the speaker may
be returned to only his own mind, to isolation. He is, perhaps,
still alone. Not surprisingly, the very short list of things he
cannot be ("Not fly or star"), which is positioned near the end
as a recapitulation of the poem's progress, leaves out all the artificial
comparisons of stanza two, confirming both their artificiality and
his closer proximity to them. He is not necessarily not like
them, including that bright machine.
Certainly these marks and admissions of artifice
make the poem a much more equivocal statement about the "organic"
possibilities of poetry than optimistic readers might have expected.
"Mayflies" forces us to complicate Randall Jarrell's neat formulation.
Here Wilbur has not just seen and shown "the bright underside of"
a "dark thing." In a poem where the speaker stands in darkness looking
at what "animate[s] a ragged patch of glow" (l.4), we are left finally
in a kind of grayness. We look from darkness into light and entertain
an enchanting faith that we belong over there, in the immortal dance,
but we aren't there now. We are in the machine-shop of poetry. Its
own fiat will not let us out completely.
Works Cited
Jarrell, Randall. "Fifty Years of American
Poetry." The Third Book of Criticism. NY:
Farrar,
Straus & Giroux, 1969.
Wilbur, Richard. "Mayflies." Mayflies: New Poems and Translations.
NY: Harcourt Brace, 2000.
Does
God Care About Mayflies?
Dr. Helene Tallon Russell
Religious Studies, Allegheny College
The theological problems posed by mayflies: does
God care about mayflies? What good are these mouth-less creatures?
Will they get mouths when they get to heaven?
The Christian tradition has typically asserted that
the non-human animals, including mayflies, are valuable to God at
least instrumentally. In other words, the animals have an indirect
value. They provide beauty or a lesson or a food and clothing for
humans. St. Augustine does argue that creation has intrinsic value
as well-- they are valuable in and of themselves, without regard
to how humans use them or their byproducts. His most well known
example is of thorns and thistles. He argues that thorns and thistles
may be by God to inflict punishment for sin, as mentioned in Genesis
3: 18, but these plants used were not created for this purpose exclusively.
Before the sinful fall, he writes that "these plants had a place
on earth."(1) But Aquinas
sees the creation as little more than the context for history of
human salvation. Typically, Christian church members don't hear
many sermons on the fate of mayflies or any other non-human animal.
However, John Wesley, the founder of Methodism,
offers a different perspective in his 1788 sermon entitled "The
General Deliverance." In this sermon, Wesley argues that God does
indeed care about animals. He bases this sermon on the passage in
Romans 8: 19-22 where St. Paul writes that the whole creation groans
together in painful anticipation of the new era. In the creation
story God says, "let us create humanity in our image and likeness."
The Christian tradition has typically interpreted this passage as
claiming that humans are a special creation, distinct from the other
animals by this Image of God. Just what is this unique character?
St. Augustine suggests that it is free will. Others have suggested
that it is rationality and understanding. We see the secular version
of this belief in the claims that humans are unique in the animal
world by their ability to use tools or language. (The claims of
the uniqueness of these characteristics have been exaggerated and
sometimes, just plain, wrong.)
Wesley tackles this theological question as a kinder,
gentler theologian. He says that the image of God is not about rationality
or understanding. Anyway, animals obviously have the ability to
understand -- look into the eyes of your horse when you talk to
it (or your parrot); the animal is not dumb, it understands. Rather,
Wesley suggests that the image of God is in capability for God.
He writes, "man(sic) is capable of God, the inferior creatures
are not. We have no ground to believe that they are, in any degree,
capable of knowing, loving , or obeying God.")(2)
Yet, he argues that we don't know for certain what capabilities
animals possessed before the corruption of creaturely nature that
occurred in the fall into sin. But we can surmise that they had
the ability of self-motion, freedom, and understanding. Wesley suggests
that all the animals lived in harmony with each other: humans, tigers,
horses, birds, lambs. Further, all creatures were immortal. With
the sin of Adam and Eve, all the creatures, human and animal, suffered
losses in their mental, physical and volitional abilities.
Wesley goes on to hypothesize about what is in store
for animals in the coming of the new age. Wesley imagines that since
St. Paul tells us that we will become like unto the stature of Christ,
something as transformational is also in store for the animals.
Perhaps, the animals will be given self-consciousness and rationality.
Perhaps they could become the Image of God. Wesley conjectures
that God may be pleased to "raise them higher in the scale of beings,.
. . to make them what we are now, -- creatures capable of God; capable
of knowing, loving , and enjoying, the Author of their being."(3)
Perhaps, they could also be brought into the perfect likeness and
stature of Christ. Of course we don't know with certainty.
To return to two of the original questions, What
good are mayflies? and Does God care about mayflies? I believe that
Wesley's answer would Yes, God cares about mayflies. If God doesn't
love all the creatures, He sure created a lot of them for nothing.
Using the biology available to him in 1788, Wesley recounts that
animals must have more than strictly instrumental value since there
is no human use for all of them. He asks rhetorically, "If there
be eight thousand species of insects; . . . who can tell us of what
use seven thousand of them are?" His answer to what good are the
mouth-less mayflies would be similar to his response to what good
are eight thousand species of insects. He writes, "consider how
little we know of even the present designs of God, and then you
will not wonder, that we know still less of what he designs to do
in the new heavens and the new earth."(4)
In other words, God must have given the animals their own intrinsic
value, since there are so many more types of animals than we could
find uses for. Further, Wesley uses this opportunity to emphasize
the glorious mystery of God. He suggests that since we are not privy
to God's mysterious ways, it is best to treat all creatures with
a loving kindness and mercy as God shows us. He says that not only
does God care for the animals, including the mayflies, but also,
"not one of them is forgotten in the sight of our Father which is
in heaven."(5) The animals,
like humans, are individuals to God.
I praise Wesley for his sensitivity to consider
the fate of animals -- and especially to see the innate value of
all of God's creatures. His imaginings are insightful and generous
as well as reasonable and consistent, and not to mention Biblical.
It makes sense that God would "redeem" the whole world and its creatures,
not wasting anything. Furthermore, Wesley's emphasis on God's mystery
and mysterious ways is consistent with the tradition's claim of
God's holiness, power, and creativity. He reminds us that we don't
know what God will do with the animals, but whatever it will be,
it will be glorious. I think Wesley is extraordinarily forward thinking
for the eighteenth century. I only wish most of the Methodists and
other Christians read his thinking on this subject today.
However, I see that Wesley is not immune to the
anthropocentrism of most of Christianity. Crudely put his hypothesis
is that the "brutes" could become like unto the stature of man(sic).
And so we should treat them kindly. Wesley wants to imagine something
glorious for all of God's creatures and what he imagines is that
they will become like us. This view not only reveals his human-centered
worldview, but it also comes dangerously close to claiming that
humans are related to animals as Christ is related to humans. I
am sure that Wesley would see the error in this claim. I would add
to Wesley's imagined suggestions that God may have something entirely
better in mind for mayflies and their comrades than to become like
humans.
Yes, God does care about the mayflies. God has unimaginable
and glorious possibilities in store for humans and for the mayflies.
Yet, I don't know if God will give mouths to mayflies in heaven.
I don't even know if the mayflies would be happier with mouths.
I suppose that is an issue only for God and the mayflies to understand.
Notes
1
St. Augustine, The Literal Meaning of Genesis, translated
by John Hammond Taylor (Ramsey, New Jersey: Paulist Press, 1982).
Chapter X, paragraphs 2.
2
John Wesley, "The General Deliverance,"
in Wesley's Collected Works, (New York: Lane & Tippett
for the Methodist Episcopal Church, 1847), p. 51.
3
Wesley, p. 55.
4
Wesley, p. 56.
5
Wesley, p. 56.
