A Fly by Any Other Name
Tipula paludosa has many names. In the United Kingdom, where the species is native, the British know it as daddy long legs, baffling Americans who assign that name to an arachnid. Scotland skews female, with Jenny long legs. The Irish, meanwhile, might refer to it in Gaelic as snáthadán an phúca, the hobgoblin’s little needle. In the United States, where the insect is invasive, Mainers have whimsically dubbed it the gollywhopper. Others in the U.S. call it the mosquito hawk, or skeeter eater, for the mistaken belief that it gobbles mosquitos. Residents of all these places, though, also know it simply as a crane fly, so named for its long, spindly legs, which act as sensors for obstacles and help balance flight.
The profusion of aliases may have something to do with the startling number of European crane flies that emerge each year, usually peaking sometime between June and September. In addition to attracting human attention, hatching in great numbers all at once stacks the odds that males and females encounter one another, breed, and produce eggs during the short time they exist in their final form as flies.
In fact, crane flies spend the majority of their time on Earth as larvae under another name, leatherjackets, which refers to their tough integument. Living for at least nine months in the soil of grassy ecosystems, leatherjackets devour plant roots and other organic matter, releasing nutrients and leaving clearings for new plants to germinate. These behaviors have led to yet more name-calling when the insects take up residence in lawns, golf courses, and farm fields.
Researchers aren’t exactly certain what combination of factors cause crane fly populations to vary from year to year and place to place, though climate and precipitation have something to do with it. One study even suggests that moisture-influenced cannibalism among leatherjackets could contribute. The larvae have large jaws, a general dislike of one another, and have been shown to move through the soil until they find optimal moisture. In years with adequate rainfall, they are less likely to meet each other because there are more places to go. When it’s dry, though, the number of suitable pockets in the earth shrinks, bringing leatherjackets into direct competition more often. The victors in these fights often kill and consume their opponents. With fewer leatherjackets overall, fewer pupate, and fewer flies emerge.
Regardless of the scale of emergence, newspapers often report on annual crane fly peaks as if they are unusual plagues. The insects are large enough to alarm the more squeamish among us, reaching up to 3 centimeters in body length alone. But crane flies aren’t monitored well enough to track their overall numbers, and they may be declining alongside other insects, with serious consequences for species that depend on them as food. Leatherjackets help sustain a variety of birds, including the red-billed chough (Pyrrhocorax pyrrhocorax) and starlings (Sturnus vulgaris), as well as mammals like shrews, hedgehogs, moles, and even badgers and foxes. And similar to the way that salmon carry nutrients from the ocean inland when they return to their natal rivers to spawn, adult crane flies lift proteins and other nutrients from the soil into the air, where their enriched bodies help fatten swooping swallows and house martins (Delichon urbicum) preparing for migration, as well as bats and other creatures.
Photographer Alex Hyde captured this image of a female crane fly on a fall morning in the Peak District National Park in England. He had set out to photograph the scenery—with low clouds and mist filling the valleys like water—when he stumbled upon “vast numbers of crane flies clinging to the tops of grass stems,” he says, all of them “covered in dew.” When he looked more closely, he noticed that each jewel of water contained a tiny, inverted image of the surrounding landscape—a reminder of the outsized role that these tiny-yet-numerous creature play, carrying whole worlds upon their spindly shoulders.
Peak District National Park, United Kingdom
Alex Hyde is a freelance natural history photographer. Whether in a tropical rainforest or his own back garden, he specializes in the smaller organisms that are so often overlooked. He is based in the Peak District National Park, UK and runs tours and workshops on macro photography.
Sarah Gilman is a writer, illustrator, and editor who covers the environment, science, and place from rural Washington state. She's also a contributing editor at Hakai Magazine. Her work has appeared in The Atlantic, Audubon, Smithsonian, High Country News, National Geographic, and others.