Top pests to look out for during the City Nature Challenge - according to Jon

Jon Sullivan recently spoke at an event held at Turanga about a few things he would like us to look out for during the CIty Nature Challenge. These are his words (in summary):

"These are some of the things that are showing up recently around Ōtautahi that hadn't been seen before. They are showing up because iNaturalist is working and people are finding them.

The world is warming - if you haven't heard - which means stuff comes across Australia, gets established in the North Island and is moving southward. We're constantly getting this trickle of new things showing up in Christchurch. Here are some I’d like you to look out for:

Hairy-legs groundsel
It first came in and was found by Auckland botanist Ellen Esler in his garden or close to his garden. It’s an Australian species.

There were only five observations of this from Christchurch until April 6. It was only known from around the containers on Port Hills Road in Ferrymead, but then it showed up, at McLean's Island so suddenly it's jumped so that's interesting. It looks quite distinctive; three finely divided leaves and it's got the hairy stem which separates it from a similar thing which is why it's called hairy-legs groundsel.

The cool thing is that this was first discovered in The South Island on iNaturalist and its spread has been showing on iNaturalist.

American ragwort aphid
The next one, which I'd like you to look out for, is the American ragwort aphid. It’s from America and eats ragworts and groundsels and fire weeds (Senecios). It’s the first aphid we have had in the country that just goes for this kind of plant. Most New Zealand native plants have never had aphid herbivory before but we have some critically endangered threatened Senecios out there in the hills. And now we have an aphid, which is specializing on Senecios. It was detected in the last city nature challenge last year in Christchurch, and Auckland simultaneously. MPI looked at it and said, ‘can we stop that?’ And then they said, ‘no, it's an aphid and it's just showed up in two different centre, we have to give up, but it's still spreading’.
I'm still the only person that seen these aphids in the South Island in Christchurch, but I'm sure you are walking past them.

Harlequin ladybirds
We've seen the explosion of Harlequin ladybirds thanks to the City Nature Challenge. It's the biggest ladybird we have by long shot so it's distinctive. And it eats any soft bodied small things it can get, including the larva of our native ladybirds. In United Kingdom when it got there, there was a big decline in their native ladybirds.

Passionvine hoppers
These are all over parts of the city now. And they are not just generous feeders on plants, but they spread diseases - move viruses around from one plant to the other. They're not necessarily a good thing to have around. There's been a real spike in the numbers in Christchurch as more people have seen them.

Steel blue ladybirds
These are an Australian ladybird common in the North Island. This is another one that has just come up in the last few years in the city nature challenge. They're really beautiful things and really jewel-like ladybirds with a very distinctive colour. I tend to find it associated with those passion vine hoppers. I imagine its feeding on their nymphs. So, keep a lookout for these as there's relatively few observations of these in Christchurch, and mostly in the Cashmere hills, but that might be just because that’s where I live. So it would be nice to know where else they are, and what they're doing.

Little hump spider
These new species come in from Australia, they land here and they spread out and it's really interesting to learn about how quickly these spread and what habitats they go into. This was first found in 2012 , but they've spread. I think they were first seen in Hoon Hay but they’ve got all the way North to Pegasus and South to Leeston, Prebbleton and Lincoln - a slow motion explosion of tiny little spiders creeping across the landscape. They make a very messy web and they're sort of semi-social, so you have lots and lots of little spiders, sharing the same web complex. They also don't use venom to kill their prey; they wrap them in massive amounts of silk and suffocate them.

South African praying mantis
These have been seen in Christchurch. Climate modeling from the University of Auckland suggests they will do well here. And if you look in the North Island, you don't find many native mantis at all now, because the male's try to mate with the females and these females are bigger than males and the eat them. They have a very narrow thorax like an hourglass shape, unlike the shield shape of our native one, and they don't have the big blue spot on the front leg that our native one has, so look out for those."

Posted on April 19, 2024 12:10 AM by smankelow