S&P’s wildlife spotlight: stick insect (Niveaphasma annulata)
A pair of mating stick insects on a blackberry plant in our backyard. Photo by Paddy Kemner.
This month, we’re putting the focus on one of our favourite (and most popular) designs - the stick insect! We’ve always been fascinated by these amazing insects - that really do so convincingly resemble sticks! But, since moving to our new home in 2020 - where there happens to be a healthy population of a particular species (Niveaphasma annulata) - our interest in them has grown even more!
Stick insects in general rely on camouflage to avoid being eaten - a common strategy among many animals. It is remarkable just how much they look like sticks; and it really take a good eye (or a bad background choice on the stick insects’ behalf!) to spot them amongst the foilage.
Niveaphasma annulata is a relatively common species in the southern half of the south island of New Zealand. While Niveaphasma is the smaller of the stick insect species in NZ, it makes up for its size with its incredible colour variation - varying from bright green, to dark or red-brown, or grey - and almost every mottled variation of those colours in between! They tend to be bright green when they are young, and as they mature their colour changes.
Perhaps one of the most notable thing about this species is that it is one of a few stick insect species that can survive in alpine regions. A study by Alice Dennis and others looked at whether Niveaphasma could survive winter in mountainous areas where it regularly gets below freezing. They made little ‘cages’ around some of their favourite plants, and put a number of individuals inside each cage. When the researchers returned in the middle of winter, they did manage to find both live nymphs and adults in the cages - even though some of the sites had experienced freezing conditions! This suggests that both young and old can ‘over-winter’ in these cold montane locations - rather than dying off over winter with a new generation born in the spring. A further study by Alice tested their freezing tolerance by exposing them to a 6hr freezing event, and found that Niveaphasma from a variety of populations could survive - except for those from Dunedin! Our more ‘balmy’ winter conditions might mean that they don’t need this adaptation to survive compared with their more mountainous compatriots!
Relatively little else is currently known about these stick insects; but… we are hopefully going to change this! With a very healthy population in our own backyard - Paddy has been going out every second night (yes, stick insects are actually nocturnal!) to count the numbers of emerged individuals that he can see. After about nine months of carrying out his survey, we’re already seeing some nice trends in emergence patterns - with a bit of a winter dip… we can’t wait to see how this pans out after a whole year!
One of the cool things that we often see is pairs (or sometimes even three-somes!) of mating stick insects! In Dunedin, Niveaphasma reproduce sexually - but apparently there are a couple of montane populations which consist of just females who clone themselves! This is also seen in other stick insect species; the Prickly Stick Insect is entirely comprised of females who clone themselves (parthenogenic), while the Giant Stick Insect can clone themselves when there’s no boys around to mate with (facultatively parthenogenic)! How amazing!
A stick insect three-some! Photo by Paddy Kemner.
When we made our stick insect print - we printed it on to a couple of t-shirts, just to see how they would sell - and… a year later - it is one of our most popular designs!! So, to celebrate our Niveaphasma print - for the month of September (2022), we’ve got 10% off all our Niveaphasma stick insect products in our Etsy shop! Shop now!
