The batwinged cannibal fly, found only in New Zealand and believed to be one of the world's rarest flies, is in danger of extinction, government officials say.

Mike Meads of the Department of Scientific and Industrial Research said the fly is found in the rugged and isolated Fiordland region in southwestern New Zealand and has only been spotted about three times in the past century.Although little is known about the fly's life cycle, Meads said it is probably in grave danger of extinction.

No larvae of the fly have ever been found, and an entomology team failed to find the fly last year.

It was first discovered in 1901 at Milford Sound. Ten years later, one was seen eating a caddis fly, commonly used for trout fishing.

The most recent sighting was in 1989 near Milford. There have been few other reports of the fly.

Meads said it would be hard to study a species so seldom seen or to estimate its population size.