Insect populations are "threatened worldwide", with only resilient species such as urban cockroaches bucking a trend that has significant implications for animals that rely on them, Australian-based researchers say.

While butterflies might inspire poets and even beetles foster empathy, many are in sharp decline compared with generalist and resilient species such as roaches that are highly adaptable and at home in forests and cities alike.

Urban cockroaches might do well amid a collapse of insect populations globally. Credit:Pat Scala

While Australia's insects are most likely tracking the same downward spiral as in Europe and North America, given the use of similar farm chemicals, poor knowledge of local species makes it harder to gauge the impact of the decline, Francisco Sanchez-Bayo, an honorary associate at the University of Sydney, said.

Australian entomologists "are a rare species themselves", Dr Sanchez-Bayo said. "We cannot do studies long term and we can’t do it all across Australia – it’s too big. We don’t have the human resources."