Flies as Pollinators

This post comes from Cliff Brock, who is a graduate student in the Contreras (plant breeding), Langellotto (pollinators), and Lambrinos (invasive plants) lab groups. Cliff is studying the impact that plant breeding has on invasiveness and pollinator visits in butterfly bush (Buddleja davidii) and its cultivars. Having three co-advisors can be extremely challenging. However, Cliff has been a true joy to work with, and seems to have navigating the complexities of three labs, quite well.

Cliff decided to write about flies as pollinators. When I asked him why he wanted to write about flies, he mentioned that they usually pollinate flowers that have foul smells, or that may not be as attractive as other flowering plants. He said that he has a special place in his heart for these ‘botanical underdogs’ ~ a sentiment that I thought was sincerely sweet.


While bees deservedly get most of the attention regarding their pollination services, many of our most important crops and wildflowers are primarily pollinated by flies.  Generally speaking, fly-pollinated flowers are dark maroons to reds and emit earthy, fermented, or putrid aromas.   The coevolution of plants and flies has resulted in some of the most amazing and unusual flowers.  The largest flowers in the word, Amorphophallus and Rafflesia, are almost exclusively pollinated by flies and beetles.And even our beloved chocolate requires a small midge fly for its sole pollinator. 

Rafflesia is a genus of parasitic plants from SE Asia.  Some have blooms 39″ in diameter.
Photo Source: https://en.wikipedia.org› wiki › Rafflesia

Here in the US, many of our most beloved spring ephemerals have coevolved with flies.  While many Trillium are bee pollinated (e.g. the abundant white Trillium ovatum), species with red and brown flowers are primarily pollinated by fungus gnats.  The iconic American pawpaw (Asimina triloba), which has seen a resurgence in popularity, smells of rotting flesh and is irresistible to a whole host of fly species.

Here we see Trillium erectum (or stinking Benjamin) absolutely covered with fungus gnats.  Photo from Brooklyn Botanic Garden

Asarum, or wild ginger, is a generally diminutive herbaceous plant often grown as a groundcover.  The odd flowers are born close to the ground and are usually hidden from human view.   Yet I find them particular beautiful, and every year I look forward to rediscovering them beneath the mottled foliage.  Asarum takes fungal mimicry to a new level.  Panda ginger, one of the Asian species, is especially funky.  The flowers mimic the colors, textures, and smells of toadstools.

Asarum maximum (as seen on the left)might have evolved to mimic a woodland fungus somewhat like the black morel, below.  Wild ginger photo from Plant Delights Nursery. Morel photo from Ohio mushroom society.

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