More ‘What did you do in your summer holidays’

Hamish Patrick, an undergraduate at Lincoln University, was awarded a summer scholarship to survey the Lepidoptera fauna of Otamahua from November 2009 to February 2010 with his supervisor Mike Bowie. Light-trapping on Otamahua involved using a powerful mercury-vapour lamp powered by a portable generator. During his nocturnal forays Hamish collected, curated and identified many species over his summer scholarship and has increased the known Lepidoptera taxa on Otamahua to 149 species. Some of the species collected were thought to be rare including an undescribed Eudonia species that feeds on moss of coastal rocks.

Otamahua an island in Lyttelton Harbour, Banks Peninsula is being ecologically restored by the Quail Island Ecological Restoration Trust. The Trust has planted 80,000 trees over the last ten years and introduced mammals have been eradicated. The ecology of the island is changing and with the flourishing vegetation some native bird species are increasing in abundance. Flying insects, like birds, can recolonise the island once habitat requirements are met.

Larvae of or Lepidoptera (moths and butterflies) are herbivores that feed on a large variety of plant, moss, lichen and other vegetative matter. New Zealand has about 2,000 species of Lepidoptera of which 92% are endemic (not found anywhere else), the highest in the world. Monitoring Lepidoptera in an area can provide a measure diversity that can be compared to other sites of similar habitat. Recommendations from his report suggest supplementary planting of larval host plants to enhance habitat for the rarer moth species.

The Canterbury Knobbled Weevil (Hadramphus tuberculatus) was thought to be extinct since 1922 but was recently rediscovered in 2004 in Burkes Pass Scenic Reserve. H. tuberculatus is a large, flightless weevil that lives on a specific host plant known as speargrass/Spaniard (Aciphylla aurea and possibly other species). The Department of Conservation gives this weevil its highestconservation status and it is perhaps New Zealand’s rarest invertebrate.
Sam Rowland spent her summer searching for this weevil with her supervisor Mike Bowie in some exciting places such as Burkes Pass, Mackenzie Pass, Hakataramea Pass, Mt Somers and Lake Coleridge. During her scholarship she collected many invertebrate species on Aciphylla. Peter Johns and Sam Brown were kind enough to identify some of the specimens she gathered, and it was found that some interesting species were collected.

There are numerous threats thought to decrease the population of H. tuberculatus. These include fire, weed invasion, predators, possum and rabbit grazing and loss of Aciphylla habitat.
Since this summer the species was only thought to be found in Burkes Pass Scenic Reserve. Many years of sampling in areas where the Canterbury Knobbled Weevil was known to be present in the past or where Aciphylla is distributed has turned up negative for the species. This year Emily Fountain, Ben Wiseman and Sam Rowland found a new population adjacent to the Burkes Pass Scenic Reserve on private farmland.

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