Rosalie Zigliani, of Oamaru, asks :-
We have recently moved to Oamaru from Auckland. What butterflies can we expect to see in this area and what should we plant so that our garden becomes their home?
Brian Patrick, an entomologist at the Otago Museum where he curates the largest collection of butterflies in New Zealand, responded.
I have records of nine butterfly species from the Oamaru area, of which the white butterfly is an accidentally introduced species, the painted lady an irregular blow-in from Australia, and the monarch self-introduced within the last 160 years. The six indigenous species are the yellow and red admirals, common tussock butterfly, southern blue, common copper and glade copper. If your area includes the surrounding mountains of North Otago, you can add a further three species; the alpine black ringlet, a further tussock butterfly and one of the boulder butterflies.
Recent research at the Otago Museum has revealed a surprising diversity of new butterflies in New Zealand, most of which were uncollected let alone described. We estimate that there are over 55 butterflies in our fauna including a small array of blow-ins from Australia. Most of the newly discovered species are boulders, coppers and black ringlets.
The idea of creating of a butterfly garden within our towns or cities is a popular worldwide. But insects have a four stage life-cycle; egg, larva, pupa and adult, each stage with its own special requirements. It is important to cater for every stage if the butterfly garden concept is to be successful. Adult butterflies need a plentiful supply of nectar at the time of their emergence from the pupa, while eggs and larva require the right host-plant, whereas the pupa stage needs a safe dry place often away from the larval host. Additionally, butterflies need heat so a north facing garden with plenty of surfaces such as rocks and tree trunks for them to sunbathe on are essential.
Three host-plants that would give results in a short time for you in Oamaru are nettles for the red and yellow admirals, pohuehue (Muehlenbeckia) vine for the coppers and clovers for the southern blue. The red admiral favours tree nettle, while the yellow will feed on any of the introduced nettles that are often found under farm windbreaks. Tree nettle is common in Herbert Forest south of Oamaru. Four of our common and widespread pohuehue species, mostly vines in forest or shrubland or mat plants in riverbeds or gravel beaches, support a superb fauna of copper and boulder butterflies. Southern blue butterflies are common in the warmer areas of the South Island and have adapted to introduced clover species as a larval host. These plants are easy to get established in lawns, roadsides and gardens.