Can the green carpenter bee of Australia be saved?

By Matt Kelly

Image of female green carpenter bee.
Female green carpenter bee | Remko Leijs

The impact of the Australian wildfires has been devastating and terrifying. The scale is almost incomprehensible. The megafire burning across the country’s most populous states of New South Wales and Victoria has engulfed approximately 2,300 square miles. And it’s just one of 135 bushfires currently burning in the southeast of Australia that have claimed over two dozen human lives, ruined nearly 3,000 homes, and possibly killed up to an estimated one billion animals. These wildfires pose a very real danger to the country’s immensely diverse insect populations. One species of native bee might now be teetering on the brink of extinction as a result.

The green carpenter bee (Xylocopa aerata) is the largest native bee in southern Australia, measuring almost an inch long (2 cm). It’s generally a solitary bee with very specialized nesting habits: dead Banksia trunks and dead grass tree stalks. The green carpenter bee is a buzz pollinator, and many native plants, such as guinea-flowers, velvet bushes, fringe, chocolate and flax lilies depend completely on buzz pollination for reproduction.

Male green carpenter bee.
Male green carpenter bee | Remko Leijs

“They’re important pollinators because they are quite large bees, therefore they need to visit lots of different plants to collect the pollen,” said Dr. Remko Leijs, a bee researcher at the South Australian Museum, in a 2018 interview with the Adelaide Review. “They go to lots of different species of flowers.”

Unfortunately, land clearing and previous large bushfires over the past century have already caused local extinction of the green carpenter bee throughout the country. While it was once widely distributed from northern New South Wales to Kangaroo Island, the bee is now found only on the western part of Kangaroo Island and on the eastern flanks of the Great Dividing Range in New South Wales.

Map of current range of green carpenter bee in Australia.

Leijs and Dr. Katja Hogendoorn, a research associate at the University of Adelaide, have been leading a dedicated effort to protect and rehabilitate the green carpenter bee population. Because Banksia doesn’t survive fire, and it requires over 30 years to regrow and get to the right conditions for green carpenter bees to use the trunks as a home, Leijs, Hogendoorn and colleagues have been installing artificial nesting stalks on Kangaroo Island. Every year, they check the nests several times, investigate the contents in the winter using x-ray, provide more stalks and remove the old ones.

At the time of the current wildfires, the team had established 440 stalks at twelve different locations on the island; 160 of these stalks were occupied with nests containing mature brood. But now almost all of those areas have burned. There may still be nests dotted around the eastern part of the island, but they’re likely far fewer in number – and the fires aren’t out yet.

Image of artificial stalk.
Artificial nesting stalk | Remko Leijs

“It is difficult to assess the situation, because there is no access to the burnt sites,” says Hogendoorn by email. “But the species is likely to be in dire straits, as all of its habitat has now either burnt or is threatened by fire, and this is unlikely to change in the coming decade.”

The bee is also found around Sydney on the east coast of NSW, but 80 percent of that habitat has been destroyed by fire as well, according to Leijs. “These fires are still burning and let’s hope there will be suitable habitat left when the fires are out,” he says by email. “So our plan are (sic) to broaden our efforts also to the Sydney area.”

One hopeful fact is that grass trees flower profusely after fire – as long as the fire doesn’t burn too hot. The grass tree stalks become available as nesting sites after a couple years and remain useable for up to six years before falling down. But it’s the artificial stalks being provided by Leijs, Hogendoorn and their colleagues that will guarantee consistent places for the green carpenter bee to nest as the landscape recovers.

“As long as the bee is still out there, we will keep going with our conservation effort,” says Hogendoorn.

You can support the efforts to protect Australia’s native bees. Donations can be made to the green carpenter bee conservation project. Leijs says donations will make it possible for the team to assess the presence of bees in the areas that remain unburned and to establish more artificial nesting stalks in and around areas that have burned. You can select either “Green Carpenter Bee” or “General native bee research” from the Designation drop-down menu to direct your support.