Sydney resident confused over 'horrifying' discovery in backyard

A Sydney man was left bamboozled after a mysterious cocoon appeared outside his home.

The puzzled St Clair resident took to Reddit on Sunday to ask for help in identifying the insect responsible for the strange addition protruding from his home’s gutter.

The resident, named James, told Yahoo7 News he was curious to discover what was making the structure after spotting several before without seeing what insect created it.

Others were equally spooked with one Reddit profile labelling the image as “horrifying”.

Several users online were quick to point out the cocoon was the product of Saunders’ Case moths –known as Metura elongatus.

And their identification matched those of experts, with Museums Victoria’s Senior Curator of Entomology Dr Ken Walker confirming to Yahoo7 News the species Metura elongatus was responsible.

“This interesting and beautiful native species of moth can take up to two years to pupate and become an adult. Only the adult male is winged, the adult wingless female remains in the cocoon,” Museums Victoria revealed.

The cocoon has its distinct appearance as the moths create it from parts of leaves and twigs.

“They make themselves a portable home out of sticks and silk, which they carry around for protection,” Western Australian Museum’s Curator of Entomology, Dr Nikolai Tatarnic, told Yahoo7 News.

Shortly after his post, James said he managed to see the bug inside and was left “fascinated”.

It’s not the first time Australian residents have been baffled by bugs, with hundreds of caterpillars descending on a Noosa home in March.