Long-tongued fly sips from afar

Insect specialized for digging deep into flowers can go shallow on occasion

long-tongued fly

LONG-DISTANCE DRINK  Prosoeca ganglbaueri, one of southern Africa’s long-tongued flies, drinks through mouthparts longer than its own body. 

Michael Whitehead

The “tongues” of South Africa’s long-tongued flies are certainly long, but they’re not flexible. So a fly has to hover at a distance to sip from a flower’s shallow nectar cup, as seen in the above photograph, which was honored in the 2015 BMC Ecology Image Competition.

The drinking tube on this particular species, Prosoeca ganglbaueri, can grow up to 5 centimeters long. When folded backward during flight, about half of it sticks out behind the fly’s body. Extreme length lets flies either dabble in shallow blossoms or reach into flowers with deeper nectar tubes. As the mouthparts of various long-tongued flies lengthened through the ages, more than 120 flower species, including Zaluzianskya microsiphon, coevolved longer tubes.

Most of these fly-specialist flowers bloom pink or white. But those color preferences aren’t inborn for the flies, says Michael Whitehead, an ecologist (and photographer of both shots) at the Australian National University in Acton. His current research reveals that flies learn color preferences based on what’s rewarding in their local floral buffet. In some places, flies learn only a narrow range of sweet colors. But in landscapes with more options, the flies willingly sip pink, white — and blue. 

long tongue fly
DIGGING IN The nectar tube of the Zaluzianskya microsiphon flower fits this fly’s long tongue like a glove. Michael Whitehead

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.

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