Fly Fascination
01-09-14
JANUARY
2014
By
Tom Turpin
Professor of
Entomology
Purdue University
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Fly Fascination
Probably more than all other insects,
flies have managed to attract human
attention. We just can't seem to avoid or
ignore these two-winged insects,
especially the species known as the
house fly.
In fact, even as I compose this on my
trusty laptop - on one of the coldest
House fly
Photo credits: Jim Kalisch
days in years here in Indiana - a small
Nebraska Entomology
fly intrudes. It zoomed past the screen
of my computer, making not one but two
passes, as if on some sort of reconnaissance mission. Searching for
what I do not know. Food? A mate? A place to rest?
After the second pass, it landed on the plastic rim of the screen and
marched upward before resuming flight. It hasn't returned. It didn't hang
around long enough for me to determine for sure what type of fly it was.
It was probably a fungus gnat, one of those fruit fly-sized flies that
sometimes surprisingly show up in homes during midwinter. That is
because fungus gnats feed as larvae in high organic material, such as
the soil in house flowerpots or debris in the trap of sink drains.
Because flies are some of the most common of insects, humans in
general and entomologists in particular have always had to deal with
them. L.O. Howard, who became chief of the Division of Entomology,
U. S. Department of Agriculture, in 1894, was no exception. In 1901 he
published a book on entomology. That book is entitled "The Insect
Book: A Popular Account of the Bees, Wasps, Ants, Grasshoppers,
Flies, and Other North American Insects Exclusive of the Butterflies,
Moths and Beetles, with Full Life Histories, Tables and Bibliographies."
As you might have guessed, the book is generally known just as "The
Insect Book."
Howard discussed a number of flies in "The Insect Book," including
mosquitoes, moth flies, gad flies, horse flies, bee flies, robber flies and
dance flies. He also devoted space to what he called "The House Fly
and Its Near Relations." Howard, in 1911, published an entire book on
the house fly called "The House Fly - Disease Carrier." He suggested
that typhoid fly was probably a better common name because this fly
can transmit the bacteria that cause typhoid fever on its feet.
The house fly and all other true flies are
classified in the order Diptera. The word
diptera means two wings. True flies are
the only major group of winged insects
that posses two, not four, wings.
In Diptera one pair of wings has been
replaced with structures named
halteres. Halteres can best be described
as knobs on stalks that function as
balancing organs in the fly. Think of
halteres in terms of the long pole that
high-wire walkers carry to maintain their
balance. Halteres are essential to flight
of the fly. Flies that have had their
halteres removed cannot fly.
Flies have structures called
halteres that are essential to
flight.
Photo credits: John Obermeyer
Purdue Entomology
Flies, especially the ubiquitous house fly, have been immortalized by
many a writer. American entomologist Vincent Dethier authored a
delightful treatise on scientific experiments using the house fly. The
book, "To Know a Fly," was published in 1966.
Even William Shakespeare noted flies in a play or two. In "Romeo and
Juliet," he writes: "more courtship lives in carrion flies than Romeo."
The lines, "As flies to wanton boys are we to the gods. They kill us for
their sport," appears in "King Lear."
The title of one of Emily Dickinson's more famous poems is "I Heard a
Fly Buzz When I Died." William Blake compares his own life to that of a
fly in his poem, "The Fly." But for most of us, poet Karl Shapiro
captures our attitude about these insects in his poem, "The Fly," with
the lines "But I, a man, must sway you with my hate, Slap you across
the air and crush your flight."
But leave it to the master of American whimsical verse, Ogden Nash, to
ask the ultimate question about the value of flies. He poses the
question in his poem, "The Fly." The poem goes "God in his wisdom
made the fly and then forgot to tell us why."
OK, Ogden, here are three good reasons for flies: they provide food for
a lot of animals and some plants, such as the Venus fly trap; they
dispose of dead plants and animals (through what they eat); and a few
of them pollinate plants. Even the despised house flies have a good
side!
Writer: Tom Turpin
[email protected]
Editor: Olivia
Maddox
[email protected]