What, no wētā?

Night-time walks in the garden

June 2025

I have only had a few excursions into the garden at night, despite the beautiful garden lighting that illuminates the foliage adjacent to the boardwalk. I've had to persuade my husband to not put those spotlights on a daily timer, because we don't need more light pollution in Auckland. The poor night-time insects would be even more confused.

A native leaf-veined slug spotted at night in the garden

On those journeys into the garden, head torch on head and camera in hand, I've noticed what is different from my night-time excursions into Linley Reserve back in Hillcrest. There the holes in the trees were filled with Auckland tree wētā, but in the new garden they are filled with spiders.

Now, I can imagine an argument against both based on their Hallowe'en looks and their sociability. I have only overcome some of my fear of spiders by studying those I've encountered in Linley Reserve over the past ten years. Whilst I'm less jumpy now - I once threw a book across a room because I turned a page and there was a picture of a spider - I can appreciate that there are a lot of people who would rather avoid them. Fair enough, but I'm still going to put their photos in the blog. Just don't throw your phone.

Banded tunnelweb spider in a hole in a māhoe tree

Auckland tree wētā are quite bizarre invertebrates, with the males looking like their monstrous jaws would give them severe neck ache and the females like they could joust with those oversized ovipositors (the curved spear that helps them lay eggs). In comparison to the other wētās in New Zealand, it definitely got hit with the ugly stick. But I miss seeing them and have gone out looking for them specifically. It somehow feels like the garden isn't healthy without them.

Female wētā at a tree cavity entrance, Linley Reserve, April 2024

So why aren't they in my garden? My first thought was because there are raspy crickets, Pterapotrechus salomonoides, an introduced species from Australia, and they might have displaced the native tree wētā. I didn't see them in Hillcrest, but they are well established in the Birkenhead garden. Danilo Hegg, another iNaturalistNZ user and wētā expert, says in his journal article this year that it is too early to tell the impact the raspy cricket is having on the ecosystem. Given he's a scientist who studies wētā, he'd probably be the first person to know whether the Australian interloper was displacing the local wētā. It probably means its unlikely they are specifically the reason there are no wētā. Besides, I've just read that rats, hedgehogs and ferrets are the biggest predators of wētā now, and I imagine they would have a much larger impact on wētā than a competing introduced species.

Google had the academic goggles on the night I did some online searching for answers, so I also happened to find an article about what Auckland tree wētā eat. This was fascinating and whilst it was based in the Waikato, which has a different range of trees than Auckland, it gave me the a-ha moment I was looking for.

Tree wētā love chomping on a wide range of plants with high levels of lipids and oils - māhoe, tōtara, kahikatea, putaputāwētā and miro, as well as the less oily kanuka. Whilst we have mahoe and kanuka in the garden here, we don't have any of the others. On the other hand, Linley Reserve is known for its large tōtara and has good quantities of māhoe, kahikatea and putaputāwētā. It seems if I want to attract tree wētā, I need to grow more of their favourite foods.

And to come full circle and because Google threw that in the mix too, what do wētā think about garden lighting? Basically they are less likely to come into illuminated areas, but the males much more so than the females. They are an important part of a number of native predators' diets, as well as invasive predators, and they are more likely to be discovered if they can be seen. So if I manage to attract wētā, I am more likely to keep them if I don't turn on the outdoor lights.

References

Hegg, Danilo. (2025). An Australian raspy cricket established in New Zealand, Pterapotrechus salomonoides (Orthoptera, Gryllacrididae), with notes on ecology and first description of the male. Journal of Orthoptera Research. 34. 77-94. 10.3897/jor.34.134391.

Brown, M. (2013). The Diet and Nutritional Ecology of the Auckland Tree Wētā Hemideina thoracica (Thesis, Master of Science (MSc)). University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/8771

Bridgette Farnworth, John Innes, Catherine Kelly, Ray Littler, Joseph R. Waas,

Photons and foraging: Artificial light at night generates avoidance behaviour in male, but not female, New Zealand weta.

Environmental Pollution, Volume 236, 2018, Pages 82-90, ISSN 0269-7491,

https://doi.org/10.1016/j.envpol.2018.01.039.