'One in a million' blue-eyed mutant cicada is found by family in Illinois during 'apocalyptic' swarm of the noisy insects

There are trillions of noisy cicadas thought to be swarming across the US this spring.

But one in particular, found by an Illinois family in their backyard, has caught the attention of scientists. 

The bug has a 'one in a million' genetic mutation that means it has grayish-blue eyes instead of the normal red.

Greta Bailey, from Wheaton, Illinois, said her children found the bug but initially didn't realise it was so special. 

Now dead, it's been donated to Chicago's Field Museum so scientists can study it further.  

'My 4-year-old son, Jack, has been in heaven since they started emerging and has taken to collecting a lot of them,' said Mrs Bailey. 

'My daughter, Caroline, looked into his collection bucket and saw the blue-eyed one. She brought it inside and showed it to me. 

'I thought it was cool and unique and had not heard that blue-eyed cicadas even existed. I took a few pictures and Caroline let it go. 

'Well, after telling my family about it, we came to find out how rare they are and were kicking ourselves for not keeping it. 

'A couple hours later, Caroline and her twin sister Addison, took flashlights outside to go look for it where Caroline had let it go. 

'Amazingly, they were able to find it again and now we knew to not let it go.' 

The specimen is the first blue-eyed cicada ever added to the Field Museum’s collections of cicadas dating back more than a century. 

Since blue-eyed cicadas are very rare, the Field Museum’s scientists will try to sequence its DNA to potentially learn more about the genes responsible for its blue eyes. 

Scientists divide the more than 3,000 cicada species into two groups – 'annual' and 'periodical', but its the emergence of this latter group that is currently leading to a 'cicada apocalypse'. 

Shortly after a periodical cicada hatches from its egg, it burrows into the ground, where it spends the first 13 or 17 years of its life, depending on the species. 

When it emerges from the ground, it lives only four to six more weeks – just long enough to mate, fertilize or lay eggs, and start the cycle all over again.

In the US this spring, the emergence of both the 13-year and 17-year varieties is coinciding for the first time since 1803. 

This means more than a trillion of the insects will swarm over 16 US states in May and June – creating a noisy buzz as the male tries to attract a female. 

This particular 'mutant' specimen with the blue eyes is a female 17-year cicada (Magicicada cassini). 

It will be on display at Field Museum during cicada-themed events happening weekly through the end of June. 

Cicada experts say that the two North American variations of the species can produce an alarming call as loud as 105.9 decibels, or 'as loud as a lawn mower'. 

'The dual emergence is a one in two or three lifetime event,' said Dr Gene Kritsky, a professor, entomologist and cicada expert at Mount St. Joseph University. 

'This happens 12 times every 221 years, but this is the first time since 1803 that these broods will emerge together.' 

Elsewhere in the US, creative chefs are serving up cicadas dishes for people to eat because the bug is low in fat and high in protein. 

In the UK, there's only one native species of cicada – the New Forest cicada – and it's endangered and rarely sighted.