Paroa School student releasing Honshu white admiral butterfly caterpillars. Image: Murray Dawson
Our current trip was made possible for two reasons.
First and foremost, Hugh was there to support the Guardians of Paroa Taramakau Coastal Area Trust. For 2019, the Trust secured MBIE Curious Minds funding to release Honshu white admiral butterflies (Limenitis glorifica), a new biological control agent to help control Japanese honeysuckle (Lonicera japonica). Japanese honeysuckle is an environmental weed in New Zealand, and problematic in Westland (as it is in other regions). Vines grow rapidly, overtaking native shrubs and small trees. Japanese honeysuckle is one of several climbers – and numerous other environmental weeds – that challenge the restoration work of the Paroa Trust.
Manaaki Whenua – Landcare Research scientists collected the white admiral butterfly from its native range in Japan, tested it for host specificity, imported it into New Zealand in containment, and reared it to increase its numbers. The NZ Environmental Protection Authority then approved it for environmental release into his country. This recent availability provided an ideal opportunity to:
- engage students, their wider whānau and community in the science of biocontrol and what it aims to achieve
- involve them in local releases, the first for the Westland region
- hopefully in the longer-term help reduce the impacts of this invasive weed in Westland.
The trip was also made possible for Murray and Robinne thanks largely to the Curious Minds fund allowing them to extend The Great Weeds Hunt Aotearoa project into the first few months of 2019. The ‘weedy lessons’ they delivered fitted well with Hugh’s biocontrol lessons and the caterpillar releases.
Fran Cohen from the Paroa Trust welcomed us when we arrived and showed us the lay of the land. Paroa Hotel was our base and from here the West Coast Wilderness Trail runs to the south, following the roadside and coastal lagoon. The Wilderness Trail has proven very popular with cyclists and Fran showed us the extensive restoration work that she and other Trust members are doing to enhance the trail – by replacing the invasive weeds with native plants. This is a huge challenge as weeds grow rampantly in this temperate climate. Further south along the trail, the restoration plantings give way to secondary native forest which shows what the restoration area may look like in future decades. Behind Paroa Hotel runs a creek and gravel road that follows the coastline to the north and south. Harakeke, gorse, blackberry and Japanese honeysuckle are common along this disturbed habitat which provided the release sites for white admiral butterfly caterpillars.
Our first day at Paroa School began with introductions. The school is a Decile 6 primary school with a total roll of 165 students. 41 students joined us for the day, combining ‘Ngahere’ and ‘Whenua’ Y4–8 classes. Joining us were several teachers (Rianna Farr and Katie Hofman, along with Principal Vic Hygate), Paroa Trust members (including Fran and Kevin Cohen, Trish Creagh, Wendy Ross, and Karl Tolley), Lauren Kelley Community Ranger of DOC, and Joan Fairhall of the Monarch Butterfly Trust. Fran did a marvellous job engaging the wider community and bringing everyone together.
During the morning, Robinne led the weedy lessons, which included the puzzles and activities she has developed to teach what a weed is, the different types of weeds, how weeds disperse, and ecological webs. Next, Hugh spoke to the students and community about biocontrol and the Honshu white admiral butterfly. He passed around a container holding the spectacular adult butterflies for everyone to see.
Then in the afternoon we moved out of the classroom to the back boundary of the school, where the students released the white admiral butterfly caterpillars onto Japanese honeysuckle growing on the other side of the school fence. This was a full release of 1,000 or so caterpillars. The site is an ideal location for the students to see the caterpillars turning into butterflies and to make future observations on the establishment of the butterfly and its impact on the honeysuckle.
Our day with Paroa School finished with the students using the iNaturalist smartphone app to record plants growing in their school grounds.
In the evening, Hugh presented a fascinating illustrated talk to the Rotary Club of Greymouth on his biocontrol work and travels overseas.
What were some of the plants that we found?
Although the students did not have a lot of time left in the day to use the iNat app, we did record a range interesting plants growing in and around the school grounds.
Behind the back fence of the school was the area of caterpillar release. In addition to Japanese honeysuckle (Lonicera japonica), we found a mixture of weed species, restoration plantings, and native and exotic plants.
Of the environmental shrubby weeds, the ubiquitous gorse (Ulex europaeus) and blackberry (Rubus fruticosus complex) dominated, with the herbaceous Montbretia (Crocosmia × crocosmiiflora) also being locally common. We recorded two exotics that were probably planted: Norfolk Island Hibiscus (Lagunaria patersonia) and Southern Magnolia (Magnolia grandiflora). We found a good range of native plants, either growing onsite naturally or part of restoration plantings, which included broadleaf (Griselinia littoralis), hebes (Veronica species), toatoa (Haloragis erecta) and abundant harakeke (Phormium tenax).
Along the northern boundary of the school was an avenue of planted pōhutukawa (Metrosideros excelsa) trees – judging by the number of capsules forming they would have put on a good show of flowers over Christmas. On the other side of the school grounds we also found a pōhutukawa seedling – which was growing out of a crack in the paving.
Along the southern boundary we found two cultivated species that were also environmental weeds spreading into the local environment.
The first was privet (Ligustrum sp.) that appeared to be planted as a boundary hedge. Further afield, weedy privet (probably Ligustrum lucidum) was found growing along a coastal gravel road and also along the Wilderness Trail. An Illustrated Guide to Common weeds of New Zealand (2010, 3rd edition) states that tree privet (Ligustrum lucidum) is a weed in the North Island only, but this invasive species now seems to be turning up as a weed in the South Island too.
The other notable plant growing behind the southern school boundary fence is an impressively tall bamboo grove. Arrow bamboo (Pseudosasa japonica) is commonly cultivated in Westland but is spread as a weed through vegetative growth of rhizomes following dumping. A nearby patch beside the wilderness trail was found growing wild.
In total, nearly 90 observations were made of nearly 50 species around the school grounds.
