The Canterbury tree wētā (Hemideina femorata) is endemic to the lowland forests of Canterbury. Like other tree wētā, it is a sizeable insect and an opportunist when it comes to food, eating mostly leaves, but taking advantage of the protein in other insects it encounters.
Here in rural Canterbury, it’s rare to find tree wētā. Old timers talk about how you used to see wētā every time you trimmed the hedge, but in 15 years of trimming, I have seen no wētā. I’ve even put wētā houses (like bird houses, but designed to appeal to wētā) in the hedge, but have never found anything but spiders in them.
Though I’ve never seen a study of their population changes, anecdotal evidence indicates Canterbury tree wētā numbers have dwindled with the intensification of agriculture and the increased use of chemical pesticides.
I have been fortunate to raise quite a few wētā in captivity, and in doing so, I’ve become familiar with the insects’ strong smell. This smell has been their downfall when faced with introduced mammalian predators—strong enough for even a human’s nose to perceive, it acts as a beacon to hungry rats, and stoats.
But it’s not just in my insect tanks I’ve smelled tree wētā. With some regularity in the early morning I can smell them in the hedge when I pass on my way to feed the chooks.
We humans have a poor sense of smell, as mammals go. We rely much more heavily on our sense of sight for identifying things. So for years now, I’ve doubted my nose, because I’ve never seen a wētā on the property or anywhere nearby.
But not long ago, on an evening walk with my husband, we found an adult tree wētā dead on the road.
Yes! I knew my nose couldn’t be deceiving me, though I was never confident enough to declare their presence based on smell alone. Now I am. I may not have seen them in my hedge, but if there are wētā being hit on the road a hundred metres from my house, I am willing to believe my wētā-scented hedge harbours them too.