One day in May last year, Sligo-based entomologist Ryan Mitchell surveyed Union Wood in the county, an old oak woodland on the eastern bank of the river Ballysadare. It’s legally protected for its mature sessile oak habitat. Mitchell was researching flies for the National Parks & Wildlife Service. Finding species as small as flies and identifying them accurately isn’t an easy job. Mitchell used a standard technique that, by his own admission, can make researchers like him look “a bit mad” – he swished a large white “sweep net” through the vegetation and then put his head into the net and put any captured flies into a pooter, a small jar fitted with two tubes.
By chance, he swept a fern that was hanging off an old oak tree and stuck his head into the net to see what he had got. He spotted a bright yellow rostrum, or beak, on a cranefly. He had found one of the scarcest craneflies around. According to Mitchell, there are only 20 records in Britain and, until that May afternoon, it had never been found in Ireland before.
It’s called Tipula luridorostris, and it was first described and named in 1833 – rostris, from the Latin for a beak; luridus meaning pale yellow. In 1840 a Danish entomologist found and named the same fly but called it Tipula flavirostris, using the Latin for yellow, flavus. The yellow snout that caught Mitchell’s eye is the fly’s defining feature.
Many of us have encountered one common cranefly: the daddy-long-legs, Tipula paludosa, blundering about the bathroom light in late summer and autumn. Its larvae, the leatherjackets, spend autumn, winter and spring underground eating grass roots (they’re the bane of golf course managers). The fly we encounter at the window or scrabbling around a light is only the briefest final chapter.
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It’s one of 211 known cranefly species in Ireland. Mitchell believes another 20 could be waiting to be found. Most of them will never come near a house, school or apartment – their needs are much more specific than that: stream beds, in sodden moss, in bog, in ground that floods every winter or in ground that never does. Take Lipsothrix remota. It spends its early life inside waterlogged dead branches submerged in woodland streams – a fallen branch, in water and nowhere else. If the deadwood is taken away or the stream goes dry, the cranefly is gone.
For Mitchell it makes craneflies especially useful. They can tell you something plants can’t. Two woods can share the same oaks yet still be very different underneath. One is damp, old and full of deadwood, the other drier and tidier. While the plants look the same, the craneflies that live their minuscule lives can be very different.
For other species, craneflies are food. On bogs they emerge in vast numbers in spring at the same time when wading birds are raising chicks. Research in England’s Peak District found that golden plover numbers rose and fell with August temperatures two years earlier. A hot, dry summer kills cranefly larvae in the drying peat, fewer adults emerge the following spring and fewer golden plover chicks survive. Wetter bogs, the researchers found, held up better.
In Ireland golden plover breeds in just a handful of places in the uplands of the northwest. In 2019 a resurvey of their Mayo stronghold, the Owenduff/Nephin bogs, found only five breeding territories in the same 27 one-kilometre squares that, in 2005, held more than 60 pairs. Its food supply depends on wetness, and wet peat is what we’ve spent nearly a hundred years draining and removing.
For Mitchell the pressures on craneflies are familiar: drainage, peat cutting that continues even on protected habitats, coniferous forestry planted on bog, climate change, pesticide use, agricultural intensification, and the clearing of scrub. Craneflies love damp, dark, humid places. We’ve spent decades making the landscape tidier, drier and brighter. “We don’t know how much we are losing,” says Mitchell.
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We still don’t know enough about them. As recently as the early 1980s, Ireland’s list was so thin that a single visitor to the country, Hans Mendl, a schoolteacher from Bavaria, boosted it. Over three separate trips, he spent weeks driving around western Ireland with a net, stopping wherever he saw potential. His wife, he noted, put up with hours of roadside stops, while he collected 3,400 specimens of 85 species of one family of cranefly. One cranefly particularly obsessed Mendl: a tiny, pale species called Molophilus pusillus that had, apparently, only ever been found as females. He caught four near Oughterard and came back the following year to look for a male. He found 41 more flies in Kerry, every one of them female. Mendl wondered whether it needed males at all, but added that it would take someone who lived in Ireland to find out.
In Union Wood, Mitchell’s yellow-snouted cranefly is now a dried specimen glued to card for preservation and held in the Natural History Museum in Dublin. Twenty species remain undiscovered. “We can still discover species on our doorstep,” Mitchell says. The question is whether we’ll keep the bogs and woods they need long enough to find them.
