Further flax weevil finds from farthest Fiordland

Until 2016, flax weevils (large flightless protected beetles) were known from a single island in Fiordland. Recent surveys by Te Papa and Department of Conservation staff have now found evidence of them on a further 56 Fiordland islands. Here, Te Papa scientist Dr Colin Miskelly reports on the latest findings from remote southern Fiordland.

Flax weevil, Dusky Sound, November 2016. Photo by Colin Miskelly. Te Papa

Flax weevil, Dusky Sound, November 2016. Photograph by Colin Miskelly. Te Papa

What are flax weevils, and why should I care?

Weevils as a whole get a lot of bad press as crop pests or for spoiling stored cereal-based foods (e.g. flour, oatmeal, and muesli). But New Zealand has many weevil species that have fascinating life cycles and conservation stories.

Flax weevil, Dusky Sound, November 2016. Photo by Jean-Claude Stahl. Te Papa

Flax weevil, Dusky Sound, November 2016. Photograph by Jean-Claude Stahl. Te Papa

Flax weevils (Anagotus fairburni) formerly occurred throughout the length and breadth of the country, but as they are large and flightless, they have been hit hard by rat predation. Populations can still be found on a few mountain tops, plus on offshore islands scattered from the Three Kings Islands (north-west of Cape Reinga) south to Fiordland. They can be found pretty much anywhere that has flax (harakeke or wharariki) and no rats.

Flax weevil larvae, Preservation Inlet, November 2017. Photo by Colin Miskelly. Te Papa

Flax weevil larvae, Preservation Inlet, November 2017. Photograph by Colin Miskelly. Te Papa

The entire life-cycle of the weevil is dependent on flax (Phormium spp.). The larvae burrow into the roots, and the adults emerge at night to browse on the leaves, leaving characteristic ragged chew marks on the edges of the leaves.

Flax weevil feeding sign, Preservation Inlet, November 2017. Photo by Colin Miskelly. Te Papa

Flax weevil feeding sign, Preservation Inlet, November 2017. Photograph by Colin Miskelly. Te Papa

This combination of vulnerability to rodents and restricted distribution led to the flax weevil being one of the first New Zealand insects to be granted legal protection under the Wildlife Act. They have been fully protected since 1980.

Results from the 2016 survey in Dusky Sound

Until recently, flax weevils were known from a single site in Fiordland – Wairaki Island in Breaksea Sound (from where they were translocated to nearby Breaksea Island in 1991). However, a Te Papa survey of 58 islands in Dusky Sound in 2016 found flax weevil feeding sign on 28 islands. Adult flax weevils are difficult to find in daylight, when they hide among dead leaves or in the soil. However, live or dead weevils were found on five of these islands, providing confirmation that their feeding sign had been correctly identified.

Sites where flax weevil feeding sign was noted in Dusky Sound in November 2016, and on islets off the outer coast of Resolution Island in November 2017. The pink arrow shows the only known Fiordland site before 2016. Red arrows show islands where live or dead flax weevils were found. Map based on NatureWatch sightings contributed by the Te Papa and DOC teams.

Sites where flax weevil feeding sign was noted in Dusky Sound in November 2016, and on islets off the outer coast of Resolution Island in November 2017. The pink arrow shows the only known Fiordland site before 2016. Red arrows show islands where live or dead flax weevils were found. Map based on NatureWatch sightings contributed by the Te Papa and DOC teams.

The latest findings from Chalky Inlet and Preservation Inlet

A joint Department of Conservation (DOC) and Te Papa team returned to southern Fiordland in November 2017, to continue the island surveys. As in 2016, we were based on the DOC vessel Southern Winds, and our main focus was surveying for seabird colonies.

Southern Winds in Cascade Basin at the head of Long Sound. Photo by Colin Miskelly. Te Papa

Southern Winds in Cascade Basin at the head of Long Sound. Photograph by Colin Miskelly. Te Papa

Team members were briefed on recognising flax weevil feeding sign, and when time allowed we searched for adult weevils and their larvae.

Flax weevil on Round Island, Preservation Inlet. Photo by Colin Miskelly. Te Papa

Flax weevil on Round Island, Preservation Inlet. Photograph by Colin Miskelly. Te Papa

Feeding sign was identified on six islands in Preservation Inlet (including Long Sound), on 18 islands in Chalky Inlet, and on four stacks along the outer coast of Resolution Island.

Sites where flax weevil feeding sign was noted in Chalky and Preservation Inlets in November 2017. Red arrows show islands where live flax weevils were found. Map based on NatureWatch sightings contributed by the Te Papa and DOC team.

Sites where flax weevil feeding sign was noted in Chalky and Preservation Inlets in November 2017. Red arrows show islands where live flax weevils were found. Map based on NatureWatch sightings contributed by the Te Papa and DOC team.

Live flax weevils were found on only one island during the day (Round Island, Preservation Inlet). We were determined to confirm their presence in Chalky Inlet also, and so made a night-time landing at a site in the Small Craft Harbour Islands, where abundant feeding sign had been noted in daylight. Two adult weevils were soon located, justifying the effort made to return to the site.

Flax weevil on the Small Craft Harbour Islands, Chalky Inlet. Photo by Colin Miskelly. Te Papa

Flax weevil on the Small Craft Harbour Islands, Chalky Inlet. Photograph by Colin Miskelly. Te Papa

Our findings will be of value to DOC in identifying priority sites for rat eradication and control in southern Fiordland.

With many thanks to Colin Bishop (DOC) for organising the survey, Southern Winds skipper and crew Chris Pascoe and Pete Kirkman for getting us there and back safely and comfortably (and for skilfully getting us on and off so many islands), and Colin Bishop, Graeme Taylor, Terry Greene, Chris Pascoe, and Pete Kirkman (DOC), Alan Tennyson (Te Papa), Riki Parata (Kāi Tahu), and Lawrie Mead for assisting with searching for weevils and their sign.

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6 Responses

  1. Aalbert Rebergen

    Hi Colin. Great to see some old-fashioned fauna survey work taking place in 2017. Thanks for sharing your findings with us, with great illustrations and detailed maps. Am looking forward to your next article. Cheers Aalbert

    Reply
    • Colin Miskelly

      Hi Aalbert
      Good to hear from you, and thanks for the feedback
      Cheers
      Colin

  2. Mark Anderson

    This is superb – without your interest/expertise in this species, we wouldn’t know this information or be able to use it for the benefit of all species on these islands. One day, if rodents can be better controlled, it could be common to see this charismatic weevil on coastal flax on the mainland and hopefully lead to others becoming passionate about our amazing invertebrate fauna. This blog is a great way of sharing your work. Much appreciated!

    Reply
    • Colin Miskelly

      Kia ora Mark
      Thanks very much for your comments, and good to see that your weevil antennae are finely tuned for the latest postings!
      Cheers
      Colin

  3. Olwen Mason

    Fascinating! And they’re good-looking insects too. You have all worked really flat out to get so much done on that trip. Thanks.

    Reply
    • Colin Miskelly

      Thanks for your comments Olwen.
      Yes, the fine, settled weather meant there was not much down time, especially when the night work was added in.
      Cheers
      Colin

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