Forest Ringlet Butterfly

Pepe Pouri

The beautiful native forest ringlet butterfly Dodonidia helmsii is rare and found only in New Zealand. Once wide-spread, Mt Ruapehu is one of few remaining strongholds for the breed (Norm Twigge, pers comm 2020). Loss of native forest habitat and being preyed upon by introduced wasps, rodents and birds are thought to be the main causes for the decline of this beautiful butterfly. Over the last few hundred years around 70% of New Zealand’s native forest habitat has been destroyed (DOC 2020). Many of the rare recent sightings of the Forest ringlet have occurred at elevations higher than 600 m, which is beyond the altitudinal limit for introduced wasps. A resident forest ringlet butterfly population was recently found on Te Hauturu-o-Toi/Little Barrier Island once wasps and other predators were eliminated (Wheatley 2017).

The last Department of Conservation (DOC) risk ranking for the forest ringlet butterfly was "At Risk, Relict" (Hoare et al. 2015) which is a category used for animals and plants that have undergone a documented decline and now inhabit less than 10% of their former range. The Royal Society of New Zealand has predicted that, with- out intervention, there will be ongoing localised extinctions in the next 30 years (Hare et al. 2019).

The distinctive appearance of the butterfly includes wing markings that look like eyes. This is a common butterfly defence mechanism – to trick predators into thinking they are the eyes of a much larger animal, and therefore not attack. The forest ringlet’s wingspans can reach up to around 6.4 cm. They only use four of their six legs for walking. The other two are much shorter with a brush-like appearance and these are thought to be used to communicate with other butterflies. Forest ringlets are one of the most beautiful of all of our known native butterfly species. In 1991 they featured on NZ $1 postage stamps

Forest ringlet butterflies emerge in summer and live for approximately one month. The butterfly lays small eggs on the underside of certain sedges (grass-like plants) and tussocks. The young caterpillars hatch in late summer and their first meal is to eat their chrysalis (sometimes called a pupa).  Over Autumn the slim green caterpillars eat sedge and tussock leaves at night and rest during the day. The caterpillars then go into hibernation over winter, nestled into the base of a nearby plant. They wake up in spring and start feeding again. By early summer the caterpillars are fully grown (approximately 3.4 cm) and form a chrysalis to hang upside-down on a nearby plant. Approximately 20 days later a gorgeous adult butterfly emerges.

We are facing an unprecedented global emergency. Life on Papatūānuku, Earth, is in crisis and climate change will significantly increase the risk of extinction for our native species. Populations of the introduced wasps that prey on Forest ringlet butterflies are expected to increase and spread as the climate warms. More frequent and more intense wildfires are also more likely which will destroy more forest. Now is the critical time to act. If we do not our children and grandchildren will know our precious native butterflies only from museum collections.

You can easily make a difference. Websites such as https://livelightly.nz/ provide lots of information about how to live your life in a way that protects rather than destroys our natural environment. Check these information sites and make simple changes to your everyday lifestyle like catching public transport, planting native trees and flowers in your backyard, using less plastic and buying seasonal fruit and vegetables from New Zealand. Every little bit will count and if we are all committed, we will save the Forest ringlet butterfly and the other thousands of our native New Zealand animal and plant species on the brink of extinction.

References

Department of Conservation 2020. Biodiversity in Aotearoa – an overview of state, trends and pressures.

K.M Hare, S.B. Borelle, H.L. Buckley, K.J. Collier, R. Constantine, J.K. Perrott (2019). Intractable: species in New Zealand that continue to decline despite conservation efforts.

R.J.B. Hoare, J.S. Dugdale, E.D Edwards, G.W Gibbs, B.H Patrick, R.A Hitchmough and J.R. Rolfe (2015). The conservation status of New Zealand butterflies and moths (Lepidoptera). New Zealand Threat Classification Series. Department of Conservation.

S.R. Wheatley 2017 – Dodonidia helmsi Forest Ringlet Butterfly. Review of the Literature, Analysis of Current Data, and Proposals for Future Conservation. Research funded by Lottery Environment and Heritage and Auckland University of Technology (AUT).