Butterfly predators: Praying mantis

August 2025

There are two species of praying mantis in New Zealand: the endemic New Zealand mantis, Orthodera novaezealandiae, and the introduced South African mantis, Miomantis caffra. Whilst the scientific evidence isn't in yet, it is widely thought that the South African (SA) mantis is displacing the New Zealand mantis in this area of New Zealand. What is scientifically proven is that NZ mantis males find the SA females more attractive and that the SA females find the NZ males more tasty. That's right, the SA females are much more likely to eat the male if it is the NZ species and the NZ male will still try to mate with the SA female over the NZ female. I tell you, I feel for the NZ females, who hardly ever consume their mates. Hardly ever.

A female SA mantis - thin thorax (mid-body), no blue spot inside its front legs

There is a very good guide for telling them apart here from a group looking after wetlands in Canterbury. My descriptions are less useful, believe me, and for the SA species, more rude. We have both species on the North Shore, but in my old and my new garden, it was and is SA all the way.

Praying mantis are a big predator of butterflies, so I do squish the South African egg sacs, called ootheca, as well as kill the juveniles and adults. Whilst they are not yet officially a pest species, they definitely are a threat to the uncommon butterflies I am attracting and raising, let alone the poor local mantis.

The NZ mantis looks wider & flatter than the SA mantis; leaf-like. Onepoto Domain, Northcote, 2023.

Because they are native, endemic in fact (found nowhere else in the world), I would not squish an NZ mantis if it went after my butterflies, but I reserve the right to relocate it if its doing far too good a job of praying on them! I have not yet had the pleasure anyway, because the only sign of the NZ species in the new garden was an ootheca on the summer house at the top of the garden last year.

The ootheca of the New Zealand mantis

Unfortunately the new house was covered in SA ootheca when we moved in and they burst before I could find something long enough to knock them off with. Since then there have been SA mantis everywhere. As I reported in my post about raising red admirals, they have been on the nettle I put in with the admiral caterpillars on multiple occasions.

There are over three times the sightings of the SA mantis on iNaturalist than the NZ mantis in the Auckland region. Turns out that because the SA mantis have been so prevalent at the new house, I have the second highest number of SA mantis sightings on iNaturalist in New Zealand and certainly the highest in Auckland. I imagine I will win the crown in another month when the next generation of SA mantis hatch. Not the claim to fame I wish to have, but I certainly feel they are out-competing our native mantis and wish more people realised the cool praying mantis they have in their garden should be treated like other introduced predators like rats.

The frothy ootheca of the SA mantis, taken by Joseph Knight, Hillcrest

The photo above was taken by the talented local naturalist, Joseph Knight, and illustrates the frothy nature of the SA egg sac, along with its 'tail', which reminds me of serving a Mr Whippy ice cream. You can see the colour and structure difference between it and the NZ ootheca.

If you feel confident in identifying them, now is a really good time to check the walls, trees and shrubs where you live and remove (I really mean stomp on) the SA egg sacs. They are likely to hatch come spring. Think of it as helping the NZ mantis females find a local guy for some summer loving. Alternatively, you are saving the NZ mantis males from being their lover's post-coital snack.