This 'unicorn' fly trapped in 100-million-year-old amber has a horn in the centre of its forehead, capped with three small eyes. This 'unicorn' fly trapped in 100-million-year-old amber has a horn in the centre of its forehead, capped with three small eyes. (George Poinar)

Scientists have found a new species of prehistoric insect preserved in amber, a tiny "unicorn" fly with an unusual set of eyes.

The fly, found in a 100-million-year-old chunk of amber from a mine in Myanmar, has a small horn on the top of its head with three simple eyes on top, in addition to two larger compound eyes.

CBC Radio's Quirks & Quarks will have an interview with George Poinar, Oct. 31 at just after the noon news.

"No other insect ever discovered has a horn like that, and there's no animal at all with a horn that has eyes on top," said George Poinar Jr., a zoologist at Oregon State University.

The fly, dubbed Cascoplecia insolitis, represents not only a new species, but an entirely new family of insects, Ponar wrote in the journal Cretaceous Research.

Many insects that have compound eyes also have three simple eyes, or ocelli, on top of their heads, thought to help in navigating during flight.

The horn of the unicorn fly with three simple eyes on top could have let it see predators coming as it fed on pollen and nectar inside small tropical flowers. The defence mechanism was apparently an evolutionary dead end though, and the characteristic later disappeared.

"Its specialized horn and eyes must have given this insect an advantage on very tiny flowers, but didn't serve as well when larger flowers evolved. So it went extinct," said Poinar.

Pollen grains from two different plant species were found inside the amber on the insect's legs, suggesting it fed on flowers. Its unusually long legs and tiny jaws also suggest it crawled over flowers to feed on pollen and nectar. The fly also has oddly shaped, spiral antennae and grasping claws.

"One of the reviewers of the study called it a monster, and I have to admit it had a face only another fly could have loved. I was thinking of making some masks based on it for Halloween," said Poinar.

The fly became trapped in amber between 97 million and 110 million years ago. Gooey tree sap would have flowed over the fly and later hardened into a resin, leaving the fly well preserved.

The single specimen of the unicorn fly is missing only a portion of the left hind leg and part of the abdomen there. Poinar said it's unusual for the complete body and wings of an insect to be trapped in amber.