Bogong moths at Parliament House.

Bogong moths at Parliament House.

One of Canberra’s less popular tourism booms is well  under way, but attractions including Parliament House wish these visitors would stay away.

Experts say the annual bogong moth invasion has had its earliest start since 1986 and that 2013 is shaping up to be one of the best - or worst - seasons in years.

The first moths were recorded in the ACT on September 7, more than 10 days ahead of their average arrival date.

Bogong moths congregate at  Parliament House.

Bogong moths congregate at Parliament House. Photo: Andrew Meares

Brown, furry and with a wing span of about four centimetres, the moths flee rising temperatures in southern Queensland, western NSW and inland Victoria to spend summer in the cool caves of the Snowy Mountains and the Victorian Alps.

Flying at night and attracted to lights, the moths are infamous around Canberra and have been a recurring problem at Parliament House since the building first opened in 1988.

A 2005 report by the Parliamentary Library found Capital Hill formed a “giant light trap” for the moths - also known as Agrotis infusa.

A currawong bird eating a moth outside Parliament House in Canberra in 2003. The birds were reportedly dying from eating the poisoned moths.

A currawong bird eating a moth outside Parliament House in Canberra in 2003. The birds were reportedly dying from eating the poisoned moths. Photo: Pat Scala

“Parliament House ... with its elevated floodlit flagpole and extensive lighting, appears to disrupt the flight of the moths,’’ the report said.

“When the powerful lights are illuminated continuously during the night, the moths are not able to fly away.”

The report said dead moths litter the corridors of power, providing food for other pests such as carpet beetles.

Bogong moths on a rock crevice near Mt Gingera.

Bogong moths on a rock crevice near Mt Gingera. Photo: CSIRO Ecosystem Sciences

It found the infestations could not be stopped completely, but mitigation methods could limit the fallout.

A Department of Parliamentary Services spokeswoman said no special arrangements were being put in place for lighting at Parliament House despite the impact of the bogong assault.

In previous years, officials have ordered doors and windows to be closed and monitored the moth’s penetration of air conditioning systems and outside areas.

Records show the moths were first recorded as uninvited guests at a Sydney church in 1865, causing a service to be abandoned.

In the mid-1970s, bogongs invaded a new, brightly lit Canberra building in huge numbers, causing lifts to fail.

New South Wales Office of Environment and Heritage bogong expert Linda Broome said 2013 was on track to be a record year.

‘‘I have been monitoring numbers of bogong moths every year since I first started trapping possums in 1986 and myself and another colleague have also been recording dates of arrival since the early 1990s,’’ she said.

‘‘This year’s date of September 7 is the earliest recorded date of moth arrival other than one of the old records in 1980 which was September 4.’’

Dr Broome said warm temperatures and moisture in the soil were responsible for early larvae hatching, bringing forward the annual migration.

‘‘We haven’t measured the numbers yet, but just from the numbers I have noticed around Canberra and what people have said to me from Sydney and various other places, it’s looking like it will be a big moth year,’’ she said.

‘‘I love seeing the bogong moths coming because I think of them as food for my possums.

‘‘Usually the moths arrive just before the snow melts on the higher areas where the possums are. It’s a ready food source for the possums as they wake up and get ready for breeding.’’

Have you been inundated with bogong months? Do you have any tips for keeping them out? Let us know in the comments.