By Matt Walker
Editor, Earth News
Thyreophora cynophila, back from the dead
A 'mythical' fly has been rediscovered after 160 years.
Thought to be the first fly driven to extinction by humans, it was also considered one of Europe's few endemic animals to have disappeared for good.
The bizarre fly was considered 'mythical' due to its orange head, its preference for living on dead animal carcasses, and the fact it was rarely sighted even in the 19th Century.
The discovery of the fly living in Spain is "sensational", say scientists.
Some authors called this species the 'Holy Grail'
Entomologist Daniel Martín-Vega
The colourful, strange-looking fly goes by the scientific name of Thyreophora cynophila and belongs to the cheese and bone-skipper family of flies.
"T. cynophila has acquired almost mythical status among the entomological community due to several reasons which makes it a very unusual species," says Dr Daniel Martín-Vega of the University of Alcalá, to the east of Madrid in Spain.
Dead of night
It preferred to live in the cool season, whereas most flies like warmer temperatures.
It lived on the carcasses of dead animals that are in the advanced stages of decay, whereas most carrion flies prefer less rotten flesh.
The fly was also said to have had an orange head that would glow in the dark, with some 19th Century scientists writing about how it could be found at night due to its luminous shine.
And 50 years after being described, the fly suddenly disappeared, supposedly for good, with the last sighting in 1849.
Many aspects of its biology remained unknown, but the fly's niche lifestyle was thought to have contributed to its extinction, as some experts speculated that it had a preference for crushed bones, in which it would lay eggs that turned into maggots.
A carrion trap used to ensnare the fly
Changes in livestock management in central Europe, improved carrion disposal following the Industrial Revolution, as well as the eradication of wolves and other big bone-crushing carnivores could have helped eliminate the fly.
"Because of that, T. cynophila was claimed as the first case of a fly species eradicated by man," says Dr Martín-Vega.
"Consequently, T. cynophila was included, as the only dipteran [true fly], in a recent list of European animals considered globally extinct."
However, Dr Martín-Vega and colleagues have found the fly living in two separate regions in Spain.
Dr Martín-Vega's team were researching carrion flies in the country in a bid to help police forensic teams.
They use the appearance of flies on corpses to help determine where and when a body may have died and how long it has been decomposing.
Around Madrid, the researchers use carrion-baited traps to catch more than 50,000 flies which have been studied and catalogued.
"I noticed the presence of six specimens of a strange-looking fly," which turned out to be the long-lost T. cynophila, Dr Martín-Vega told the BBC.
He and his colleagues have published details of this new discovery in the journal Systematic Entomology.
While they were waiting for the paper to be published, another group of researchers also found the fly living in La Rioja Province, in northern Spain.
Dr Martín-Vega's team have also discovered an old museum specimen of the fly which they believe originated in Algeria.
"This specimen, together with the present captures in Spain, suggest that probably the species is also present in more countries of the Mediterranean Basin," he says.
The researchers want to ensure the fly is listed as a protected species, until more is known about where it lives.
"The protection of T. cynophila is essential since one of the major threats for rediscovered insects is the indiscriminate capture by insect collectors, who consider these insects species a 'treasure' for their collections," says Dr Martín-Vega.
"In the case of T. cynophila, its colourful appearance is an extra handicap, indeed some authors called this species the 'Holy Grail' of Dipterology, [the study of flies]".