The Daddy Longlegs Debacle

From False widows to Asian hornets, tales of ‘invasions’ of creepy-crawlies are a staple of the British tabloids and online news channels. The latest to find themselves in the spotlight are Daddy longlegs.

“Plague of 200 BILLION giant daddy longlegs to invade Britain” is a typical headline in this summer’s media furore. If you’ve read these articles you might recognise my name since I am quoted in them as a spokesperson from Buglife*. Hence, the following is an evaluation of these articles I’m now associated with, as well as an attempt to save face. Why? Because it’s all a bit confused

*I should stress that what I’ve written here is my personal opinion only

What is a Daddy longlegs?

You might have your own idea, but the common name ‘Daddy long-legs’ can refer to three kinds of animal. Though they all earn their title from their long, spindly legs, they are very different beasts. Here’s a guide to help you:

wildlife-articles-daddy-longlegs-pics-captioned-2

Hopefully the differences between these creatures are clear, but they have often been confused for one another thanks to their common names. This is a brilliant example of why naturalists prefer to use scientific names. As is the following:

 

Confused quotes

On the 31st of August, the Express published a sensationalist story on ‘Cannibal spiders’ invading our homes, centered on Pholcus phalangoides, including quotes from Buglife and pictures of Harvestmen. Though they are indeed a non-native species from warmer climates so are usually found indoors, P.phalangoides have been established in the UK for over a century and are harmless to humans (a bite test on the TV show Mythbusters was described as “a little tiny burning”). The article spread to various other papers.

It was therefore with Pholcus in mind that I picked up the phone to answer a media enquiry about a “Daddy longlegs invasion” and described the history of the species in the UK. Only when the article was published did I realise the mistake…cue a flurry of media stories claiming that Craneflies are non-natives that are spreading across the country.

I could only watch aghast as story after copied and pasted story invaded the mass media sites of the internet, with the misplaced quote carrying both my name and Buglife’s. Through the newspaper equivalent of Chinese whispers and a dash of forced sensationalism, my quote was even applied to the Giant cranefly (Tipula maxima) which is very much a native species (Though it can reach an impressive four inches, it lives off pond sludge-hardly anything to shout about).

It is frustrating (to put it mildly) to have my name associated with such a seemingly garbled statement, even more so when it’s stated on behalf of Buglife, an organisation that harbours tremendous expertise including the National Recorder of Craneflies. It is little consolation that confusion is rife within the media companies as well, as several articles included picture and videos of Pholcus and Harvestmen.
Lesson learned: When talking to the media, always ask for the context of their request and be as critical of their sources as you would hope a qualified journalist would be. With that in mind…

 

The ‘record breaking 200billion’

Enough about me and the spiders. What about the claims made about the real stars, the craneflies? The articles (including the one behind my phone call) focus on one particular species, Tipula paludosa. This is one of the craneflies you’re most likely to encounter, since they breed in lawns and amenity grassland (the larvae, known as ‘leatherjackets’ eat grass roots) and they emerge in late summer, when the warm nights draw in, so they are attracted to houses by our electric lights and enter through our open windows.
Like many insects, the adult craneflies emerge in a synchronised burst, ensuring that they meet up and breed before they die of exhaustion. In fact, most species of cranefly can do little else since they cannot eat as adults (lacking functioning mouthparts and a gut) so only last a few days at most.

So mass emergences of craneflies are nothing new, but is this year really a record? Finding the source of the claim took some delving into, but it’s still not completely clear.

As well as being familiar to the public, Tipula paludosa is also well studied, since the larvae’s eating habits can make them a pest of cereal crops and pastures. So it was that a newspaper article from 2015 (claiming 175 billion this time) referenced Professor Davy McCracken, Professor of Agricultural Ecology and Head of Hill & Mountain Research Centre at SRUC: Scotland’s Rural College.

Professor McCracken has an impressive portfolio of work researching how UK and EU-level farm management practices relate to the biodiversity of farmland ecosystems. Crucially, this includes leading an annual survey of leatherjacket populations in Scotland on behalf of SRUC. In the 2015 Express article, Professor McCracken explains the maths:

“While over 90 per cent of the fields sampled contained more than 0.6 million grubs per hectare nearly 60 per cent of the fields harboured populations of over two million per hectare.

If those kinds of concentrations were replicated across the estimated 12 million hectares of British grasslands, parks and lawns, the resulting crane fly explosion would be of astronomic proportions, with figures ranging from seven billion insects to a gargantuan 175 billion.”

Though this calculation has its limits, it’s satisfying to find it is based on real data. But there’s still something wrong. The Daily Mail is a year behind. The news archive of SRUC reveals that 2014 was the record-breaking year for leatherjackets, whereas the 2015 survey actually revealed a crash in numbers.
So what of this year’s record-breaking 200 billion? Amusingly, the SRUC’s 2016 survey revealed a “generally average year”….not the record breaking invasion the media is warning of then!
The earliest mention of the 200 billion figure that I could find was written by an anonymous journalist from the press association published on the 20th of August…“it was with some amount of repulsion I read that 200 billion of the bugs are due to hatch on our shores this autumn.” – without mention of where they read it.

 

So the 200 billion figure remains mysterious. Is it taken from a different scientific source? Is it a rounding up of the 175 billion figure or is it completely made up? If anyone has any clues, I would be very interested to read them in the comments.

 

Don’t Panic!

Regardless of the exact details, it seems we may not have to worry about the Cranefly armageddon after all (Not that the adult flies are anything to worry about anyway!) It is yet another storm in a teacup ‘bug scare’ stirred up by media scaremongering.  In a recent TV appearance, Dr Sarah Benyon, (of Dr Benyon’s Bug Farm) assures us that Craneflies are not increasing despite the media claims, and I’m inclined to believe her over the tabloids any day.

But wait…aren’t Daddy longlegs really venomous?
No. This is a persistent myth originally referring to Pholcus spiders – whose venom doesn’t even act strongly on insects! Though it does make good comedy:

Note: Since I began writing this, Buglife have published an official response here.

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RoryD

RoryD

Conservation Ecology graduate with a particular interest in entomology. Pleased to be a volunteer and subcontractor with Buglife. Views and fixations are my own.

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