A New Zealand Category I Threatened Species: The Flightless Spiny Longhorn Beetle

A Night at Bushy Park Sanctuary

Tom and I joined our friend and natural history curator of the Whanganui Regional Museum, Mike Dickison, and fellow naturalist, Lisa, for a night out at Bushy Park light-trapping for insects.

Whilst waiting for the trap to draw in the local residents, we took a stroll along one of the forest tracks through the native bush that covers the majority of the 100 hectare predator-free sanctuary.

On the shell-rock track, Tom spotted the subject of today’s post: a spiny longhorn beetle (Blosyropus spinosus). To take the photos, we placed the beetle on a tarata (Pittosporum eugenioides) leaf.

Blosyropus spinosus [SPINY LONG HORN BEETLE] Bushy Park, New Zealand 24-11-2017 (4)
Click to zoom in

The Spiny Longhorn Beetle (Blosyropus spinosus)

The spiny longhorn beetle is one of the largest endemic beetles in New Zealand growing up to around 8cm long. It is rare, but has been found in forest in many areas throughout New Zealand.

As the name suggests, this longhorn beetle has four large spines in front of the wing-covers and another two on the head. These spines are the key distinguishing characteristic. Like many New Zealand species, it is flightless.

Blosyropus spinosus [SPINY LONG HORN BEETLE] Bushy Park, New Zealand 24-11-2017 (5)
Click to zoom in and see the six identifying spines
The larvae tunnel into the rotting wood of dead trees such as manoao/silver pine (Manoao colensoi), native beech (Fuscospora spp.), tawa (Beilschmiedia tawa) and grass tree (Dracophyllum spp.).

The adult lays the eggs towards the top of the tree. The larvae then hatch and slowly tunnel down towards the base of the tree as they feed. At the base of the tree, each larva creates a large chamber in which it pupates. This chamber opens to the outside, but is plugged with chewed wood. After metamorphosis, the adult beetles may overwinter or hibernate within their chambers. Emergence is usually from August through to February.

Blosyropus spinosus [SPINY LONG HORN BEETLE] Bushy Park, New Zealand 24-11-2017 (1)

Blosyropus spinosus [SPINY LONG HORN BEETLE] Bushy Park, New Zealand 24-11-2017 (2)
Click to zoom in

A Category ‘I’ Threatened Species

The spiny longhorn beetle is classified as a Category I Threatened Species in New Zealand.

There appears to be some confusion as to what ‘Category I’ means, with some websites reading this as ‘Category one‘. I tried searching what exactly ‘Category one‘ meant, but was having trouble. Each website that mentioned ‘Category one‘ was referencing Andrew Crowe’s 2002 book, Which New Zealand Insect?

Upon checking the book, I noticed that it was actually written as ‘Category I’ (not 1). Using this as my search term, I managed to find the original Department of Conservation PDF document. Check out page 12, section 4.2.1 here. Also see page 545, Appendix 2 here. The mystery was solved, it is Category ‘I’ for ‘Indeterminate’.

What ‘Category I’ means is that the invertebrate is suspected to be under some form of threat, but there is insufficient information to place them in any of the other categories. Usually the invertebrate’s taxonomic status needs clarification and/or field surveys are required to establish distribution and abundance.

Blosyropus spinosus [SPINY LONG HORN BEETLE] Bushy Park, New Zealand 24-11-2017 (3)
Click to zoom in

How can you help?

As the records for this species are sparse, if you see one, make sure to get a quick photo and log it on NatureWatchNZ!

References and Further Reading

Bushy Park Sanctuary Website – Homepage – http://www.bushyparksanctuary.org.nz/
(Retrieved 1 January, 2018)

Crowe, Andrew (2002). Which New Zealand Insect?. North Shore: Penguin. p. 44. ISBN 978-0-14-100636-9

Department of Conservation Document (PDF) – The Conservation Requirements of New Zealand’s Nationally Threatened Invertebrates (2001)
Links to view ‘Category I’ references:
http://www.doc.govt.nz/Documents/science-and-technical/tsop20a.pdf  (see page 12, section 4.2.1)
http://www.doc.govt.nz/Documents/science-and-technical/tsop20g.pdf (see page 545, Appendix 2)
Link to view Blosyropus spinosus reference:
http://www.doc.govt.nz/Documents/science-and-technical/tsop20d.pdf  (See pages 267 – 288)

T.E.R:R.A.I.N Website – Beetle (Longhorn Spiny) Blosyropus spinosus – http://www.terrain.net.nz/friends-of-te-henui-group/local-insects/beetle-spiny-longhorn-blosyropus-spinosus.html
(Retrieved 1 January, 2018)

Wikipedia Website – Blosyropus spinosus –https://en.wikipedia.org/wiki/Blosyropus_spinosus
(Retrieved 1 January, 2018)

7 Comments Add yours

    1. Thank you! We were all pretty excited to come across it. 🙂



  1. Pete Hillman says:

    Amazing photos! Beetles are so fascinating!

    Liked by 1 person

    1. Thank you, Pete! Beetles are absolutely worthy of our fascination… I just did a quick calculation, and if we were to write one NZ beetle blog post every day, it would take us 12 years to get through them all! (And that’s just the species we know of 😀 )


      Liked by 1 person

      1. Pete Hillman says:

        Coleoptera are the largest insect group, so I wouldn’t be surprised, Emma. They are a fascinating and diverse group. All the best to you both for 2018!

        Liked by 1 person

  2. Pam says:

    Beetles are so fascinating. Really interesting!

    Liked by 1 person

    1. Thanks for your comment, Pam. We’re glad you enjoyed the post and our fabulous spiny longhorn beetle! 🙂



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