Pollinators: Flies

This is a continuation of our series on pollinators. In this article I will cover flies, often overlooked pollinators of many plants.

As usual, keep in mind that a lot of the plant examples are not exclusively pollinated by a single pollinator. Often there can be several different pollinators visiting the same type of flower. For example anything that a fly can pollinate is usually also visited by bees.

Large Flies

I’m generalising larger flies into a single guild, and it is likely this group can be divided up into several sub-groups, but fly pollination is so poorly studied that we do not have a very broad picture of what flies are doing on flowers.

Flies usually feed on nectar when they land on flowers. Since they aren’t as fuzzy as bees, they don’t pick up as much pollen, but some are hairy enough to transfer pollen. Mango farmers take advantage of flies by putting prawn shells around their farms. This attracts carrion flies which then also pollinate the mango flowers.

Hoverflies are sometimes mistaken for bees. An easy way to tell hoverflies from bees is their flight pattern – they fly less frantically than a bee. They are not as fuzzy as bees and usually spend more time on flowers. They also tend to have shorter antenna compared to bees.

While pollinating they hunt for smaller insects and are good natural pest control.

Examples: Hoverflies (Syrphidae), Carrion flies (Calliphoridae), Flower flies (Anthomyiidae)

Flower structure: Fly-pollinated flowers tend to be shallow and grow in clusters.

Plants that they pollinate: mangoes

Small flies and midges

Small flies are very important pollinators of important crops, without them we wouldn’t have cempedak, nangka or chocolate.

Some are very small and can hardly be seen while flying. These flies typically are attracted to downward facing flowers that are close to the ground. Some plants like Aristolochia have elaborate trap flowers that trap the flies for a while until they pick up enough pollen.

Examples: Small fruit flies (Drosophila spp.), Scuttleflies (Phoridae), Midges (Nematocera)

Flower structure: Usually not brightly-coloured, tube shaped flowers

Plants they pollinate: nangka, cempedak, cocoa, Aristolochia

Carrion feeders

This group of insects feed on carrion and other rotting material. Some plants take advantage of this by pretending to be rotting meat with foul-smelling and dark reddish or purple flowers.

While the confused insects, (usually carrion flies or carrion-feeding scarab beetles) crawl around the flower in search of food, sticky pollen gets all over them. When they give up and leave the flower, they bring the pollen to other flowers for pollination. Our famous Rafflesia flower uses this pollination system.

Examples: Carrion feeding scarab beetles (Onthophagus deflexicollis), Carrion flies (Calliphora spp., Chrysomya spp., Lucilia spp.)

Flower structure: The structure of these flowers is surprisingly varied, but they have similar traits of foul smells and dark coloration

 Plants they pollinate: Amorphophallus, Rafflesia, Tacca

References:

Ssymank, A., Kearns, C. A., Pape, T., & Thompson, F. C. (2008). Pollinating flies (Diptera): a major contribution to plant diversity and agricultural production. Biodiversity, 9(1-2), 86-89.

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This article is supported by The Habitat Foundation Conservation Grant