Caring for Pollinators - Bundesamt für Naturschutz

Ssymank, Kearns, Pape & Thompson Fact sheet pollinators: Flies (Diptera)
torhynchus longirostris (Wiedemann), which has a proboscis of 90-100 mm, which is about
three times its body length.
Nectar and pollen are usually ingested while the fly is sitting on or in flowers, but some flies
are able to hover in front of the flowers while sucking nectar (e.g., some Bombyliidae,
Nemestrinidae, Tabanidae). Some flies show learning behaviour for flower colour and nectar
reward. Flies can fly at low temperatures, and they often outnumber bees in damp or shady
places such as the understory of rainforests. Flies show an increasing dominance at higher
altitudes and higher latitudes.
Main flower preferences
Diptera form a major part of the pollinator guild for plants that are pollinated by multiple in-
sect groups. Even generalist flower visitors have been shown to contribute significantly to
fruit set. An increasing number of flowering plants are being discovered that are entirely de-
pendent on dipteran pollinators. Examples include the ‘seed-for-seed’ mutualism where spe-
cies of the anthomyiid genus Chiastocheta pollinate the closed flowers of Trollius europaeus,
and the gall midge pollination of Artocarpus integer, which is a mutualism involving also a
parasitic fungus. A significant number of flowers have specialized in being pollinated by car-
rion flies, including the world’s largest flower Rafflesia arnoldii and its relatives, and several
commercially important flowers like Stapelia spp., Amorphophallus spp. Many flies prefer
white, yellow or inconspicuous small or greenish flowers. Flat or bowl-shaped actinomorphic
flowers and umbels of the Apiaceae are commonly visited by flies. Flowers are visited not
only for food (pollen and nectar), but for several other reasons as well. For example, some
flies warm up by sitting in flower cups that face the sun; others rendezvous with mates at
certain types of flowers; some flies are are fooled or trapped by flowers (carrion flowers,
mate-deceiving flowers, funnel-traps like in the plant family Araceae or Asclepiadaceae) that
they unwittingly pollinate. Even pollinia (pollen packages) of some orchids may be distributed
by flies (the flower fly genera Microdon, Eristalis).
Flies and pollinated crops
More than 100 cultivated plants are known to be pollinated by Diptera. Among them plants
like Cocoa, where small Diptera are a guarantee for good harvests and later on chocolate-
production. Also, flies are increasingly being used for the pollination of various greenhouse
crops.
Examples for pollinated plants are:
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