Watching weevils

Department of Conservation —  17/02/2014

DOC Ranger Tansy BlissBy Chatham Islands Ranger, Tansy Bliss

It all began on a sunny Sunday afternoon, when I was chatting to another DOC Ranger, Shelly Sidley, who had just put the Chatham Island team through their paces with health and safety training.

When I mentioned the endemic Chatham Islands coxella weevil Hadramphus spinipennis, surprisingly, she responded with an interested look and then a follow up comment of, “I know just the person who would love to help you with monitoring it.”

Chatham Islands coxella weevil

Chatham Islands coxella weevil

A year later, I am on Mangere Island  with Mark Anderson — a secondary teacher of science and biology at Marlborough Boys’ College.

We’re systematically searching 455 soft speargrass plants (Aciphylla dieffenbachii) for the large, flightless Chatham Islands coxella weevil, last studied in 1996 by Katrin Schöps.

Speargrass on the coast.


In 2011, Mark, under a Royal Society of New Zealand teacher’s fellowship, undertook the first comprehensive study of the ngaio weevil on Stephens Island.

As his enthusiasm for weevils and monitoring had not diminished, Mark volunteered his practical skills, knowledge and time to help on Mangere.

Mark Anderson searching for weevils.

Mark searching for weevils on a speargrass flowerhead

During the 10 days of intensive work on Mangere Island, we revisited all the original sites where weevils had been found in the mid-1990s and systematically surveyed thirteen 25 mquadrants at night, recording how many weevils we saw and where we found them.

A weevil after heavy rain.

A weevil after heavy rain

The results were impressive. We discovered:

Soft speargrass plants with as many as nine weevils quietly munching away on leaf stems or feeding on the high protein male and female flower heads.

Weevil aggregations of up to seven weevils piggy backing each other.

Numerous weevil pairs perhaps mating.

Lone weevils, metres away from any speargrass plants, plodding across iceplant or carex.

Weevils hiding in the grass, playing dead during the day.

Weevils out in the pouring rain all glistening and dark with the moisture.

Weevils mating on speargrass

Weevils mating on speargrass

We even found weevils in the middle of Robin Bush, some 300 metres away from any speargrass plant.

As we concluded our work, confirming good numbers of weevils still present on the island, we were thankful to Shelly Sidley who made it all possible.