Why Are There So Many Bogong Moths in NSW Right Now

Have you noticed more moths than usual gathering around your windows, doors or outdoor lights lately? If you're in NSW, you're certainly not the only one.

Large numbers of Bogong moths have been spotted across parts of the state this spring, with some people finding them covering walls, clustering around buildings and even making their way indoors.

While their sudden appearance might seem like a moth invasion, there's actually a fascinating reason behind it. These native Australian moths are making their annual journey towards the Australian Alps, and their growing numbers could be a welcome sign after years of significant population decline.

So, what exactly are Bogong moths, why are there so many around right now, and should you be concerned if they turn up at your home?

What are Bogong moths?

Bogong moths (Agrotis infusa) are native Australian moths best known for their remarkable long-distance migration.

They're typically brown or greyish-brown, with patterned wings that help them blend into their surroundings. Although they might look like ordinary household moths at first glance, Bogong moths have a rather extraordinary annual journey.

Each spring, millions of these moths migrate from their breeding grounds in parts of southeastern Australia towards the cooler Australian Alps, where they spend the summer sheltering in mountain caves and rocky crevices.

Some travel distances of up to 1,000 kilometres to reach these summer resting sites.

Bogong moths also play an important role in Australia's ecosystems. They provide food for native wildlife, including the endangered mountain pygmy possum, which relies on them as an important seasonal food source.

Why are there so many Bogong moths in NSW right now?

The sudden increase in Bogong moth sightings across NSW is largely linked to their annual spring migration.

As temperatures begin to rise, Bogong moths leave their breeding areas and travel towards the Australian Alps, where they seek cooler conditions during the warmer months.

Their migration routes can take them across parts of NSW, including Sydney and Canberra, which helps explain why so many people are suddenly noticing them.

Their numbers appear to be recovering

What's particularly interesting about this year's sightings is that Bogong moth populations appear to be making a comeback.

Bogong moth numbers declined dramatically between 2017 and 2019, with estimates suggesting a reduction of up to 99.5% during that period. Because of the decline, Bogong moths were classified as Endangered on the IUCN Red List in 2021.

Researchers have linked their decline to several possible pressures, including drought, habitat loss, pesticide exposure and changing environmental conditions.

However, recent sightings suggest that their populations may be recovering, with large numbers once again being observed along their migration routes.

For scientists and conservationists, this is encouraging news, particularly given the moths' ecological importance.

Weather can also influence where they're spotted

Weather conditions can affect how Bogong moths travel and where they temporarily settle during their migration.

Strong winds, changing temperatures and other weather patterns may influence their movements, sometimes bringing large numbers into populated areas.

However, while the return of Bogong moths is encouraging, scientists are also concerned about how future weather conditions could affect their recovery.

In particular, a potential El Niño event, which is often associated with hotter and drier conditions in parts of Australia, could create additional challenges for these moths. Drought and reduced vegetation can affect the availability of food and suitable breeding conditions, potentially placing further pressure on their populations.

For now, the increased sightings are a welcome sign, but researchers will be watching closely to see whether the Bogong moth population continues to recover in the coming years.

Why are Bogong moths gathering around homes?

If Bogong moths are travelling towards the mountains, why are so many ending up on windows, walls and inside homes?

One reason is artificial lighting.

Like many other moth species, Bogong moths can be attracted to lights at night. Outdoor lighting, illuminated windows and brightly lit buildings may draw them away from their migration route.

As a result, you might notice them gathering around:

• Outdoor lights and porch areas

• Windows and glass doors

• Exterior walls and building entrances

• Garages, sheds and other sheltered spaces

• Indoor lights when doors or windows are left open

Bogong moths may also settle in sheltered areas during their journey, particularly when weather conditions are less favourable for flying.

If you notice a large cluster of moths resting on your walls or around your home, they may simply be stopping temporarily before continuing their migration.

Are Bogong moths harmful?

Despite their large numbers, adult Bogong moths are generally harmless to people. They don't bite or sting, and they're not known for damaging household furniture, clothing or stored food like some other moth species.

But are Bogong moths considered pests? Interestingly, it depends on their stage of life.

During their caterpillar stage, Bogong moths are known as black cutworms. These larvae feed on plants and young seedlings, sometimes damaging crops and pastures. Because of this, they've historically been considered minor or occasional agricultural pests, particularly when caterpillar numbers increase in farming areas.

However, once they develop into adult moths, they no longer pose the same threat to crops. The moths currently appearing around homes and buildings across NSW are generally passing through as part of their annual spring migration, rather than causing a household infestation.

What should you do if Bogong moths enter your home?

If you've noticed Bogong moths gathering around your home, there's usually no need to panic or reach for insecticides.

Because these moths are important to Australia's ecosystems, experts encourage people to remove them gently and avoid harming them wherever possible.

Here are a few simple ways to manage their presence.

1. Turn off unnecessary outdoor lights

Bogong moths can be attracted to artificial lighting, so reducing unnecessary outdoor lighting at night may help prevent large numbers from gathering around your home.

If possible, switch off porch lights or other outdoor lights when they're not needed.

2. Keep windows and doors closed

If moths are appearing around your home, keeping windows and doors closed during the evening can help prevent them from entering. Flyscreens can also provide a useful barrier while allowing fresh air to circulate.

3. Gently guide moths back outside

If a Bogong moth makes its way indoors, try switching off the indoor lights and opening a nearby window or door to encourage it to leave.

You can also gently capture the moth using a glass or container and a piece of paper, then release it outside. Avoid handling the moth unnecessarily, as its wings can be delicate.

4. Avoid spraying or killing them

Although it might be tempting to use insect sprays when large numbers appear, Bogong moths are generally temporary visitors rather than household pests. Avoid using insecticides against them where possible, especially given their ecological importance and previous population decline.

In most cases, a few simple changes to lighting and entry points are enough to help manage their presence until they move on.

A spring visitor worth protecting

Seeing large numbers of Bogong moths around NSW might be unusual, especially if they're gathering around your windows or finding their way indoors.

But rather than being a cause for alarm, their appearance is part of one of Australia's most remarkable seasonal migrations.

So, the next time you spot a Bogong moth resting on your wall or fluttering around your porch light, remember that it could be in the middle of an incredible journey towards the Australian Alps.

And if one happens to wander inside, a gentle helping hand back outdoors is usually all it needs.