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Flies (Dipterans)
are among the most common insects
that visit and pollinate
flowers. Flies have been mentioned
as pollinators or regular
visitors of thousands of species of
flowering plant. A great
variation of pollination methods is found among the plants that are fly
pollinated. Many of the pollinator flies feed on exposed fluids and also
eat small solid particles including
pollen grains. Flies are important pollinators under certain
climatic conditions because they are present at all times of the year.
Some plants may be completely dependent on flies for pollination. Even
flies that are generalists in their floral visits can contribute to
plant reproductive success, and may equal or rival
bees as effective pollinators
in some.
There are two types of fly pollination, myophily and
sapromyophily.
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MYOPHILY (Fly pollination): In general,
typical fly pollinated flowers do not
bloom regularly and are simple
with very little depth. Flower colour is usually pale with a dull
texture. Nectar guides often occur. Nectar is open or easily
available and the male and
female parts of the
flower are well
exposed. Many of these flowers are scented, but for the most part,
the scent is imperceptible.
The "hoverflies" are some of the most common pollinators flies, they
are often brightly coloured
they are also known as pollen eaters and visit tubular or convex shaped
flowers. Adult flies feed on pollen and
nectar. (Plants that are fly
pollinated include for example: Euphorbia, Sedum and various members
of the Crassulaceae, Brassicaceae and Orchidaceae families) |
"Hover-Flies" or "Flower fly"
Scientific name Syrphus balteatus one of the most
common species of the Syrphidae
family
(Diptera
order
).
Left: On a Crassula flower (Photo by: Andrea B -
Italy)
Right: On an Echinocereus reichembachii (photo by:
Andrea Seidel (Germany) |
▲Above: In this corolla of Stapelia
grandiflora a female of "green-bottle fly" (Lucilia
sp.) comes
to ovideposit a new packet of eggs... note that a lot of eggs (the
white masses) were deposed before by another flies !
(photo by: Jean-Yves Cretin (France) |
SAPROMYOPHILY (Carrion-fly and
dung-flies pollination): Certain flies are deceived into
pollinating flowers that produce odours of decay and
mimic the
decaying flesh in which these flies normally oviposit. Typical
carrion or dung-flies are uninterested in the flowers as such, but
go to the flower "expecting" to find rotting protein. Not finding
the rotting protein, they will leave; therefore, most sapromyphilous
flowers have traps to prevent the flies from rapidly leaving. The
traps are similar to those found in the insectivorous plants and can
be one-way bristles, slipways, or seesaw petals.
Characteristics of
sapromyophilic flowers include: radial in shape, often with great
depth, or lantern shaped, frequently with window openings through
which the flies crawl into the blossom (or trap). Flowers have a
dull texture and are dark colours of brown, purple and greenish.
There are no nectar guides on the petals but often they are
maculated (marked with dark spots). Reproductive organs are
generally hidden.
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