''Anagotus fairburni'' or flax weevil is a large flightless

weevil Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...

. It feeds on leaves of New Zealand flax species where it produces a characteristic feeding notch. It is found on islands and in alpine areas of New Zealand.

Taxonomy and description

The flax weevil was described by Albert E. Brookes in 1932 based on a series of specimens sent to him by Ernest Richard Fairburn. These were collected at its type locality of

D'Urville Island D'Urville Island (), Māori language, Māori name ' ('red heavens look to the south'), is an island in the Marlborough Sounds along the northern coast of the South Island of New Zealand. It was named after the France, French List of explorers, ...

in the Marlborough Sounds in 1931. The type specimen is held at the New Zealand Arthropod Collection. It was described as large and robust in form and ranging in size from 20–24mm. Specimens can range in colour from coppery-brown to dark brown, or even black in older weevils that have lost their scales. They have distinctive pairs of

tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection ...

s mid-way along and at the base of the elytra. Larvae are large with a cream coloured body and brown head. The adult is flightless.

Distribution and habitat

This species is distributed across a wide range. It can be located from the

Three Kings Islands 3 is a number, numeral, and glyph. 3, three, or III may also refer to: * AD 3, the third year of the AD era * 3 BC, the third year before the AD era * March, the third month Books * ''Three of Them'' (Russian: ', literally, "three"), a 1901 n ...

, north of the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

of New Zealand, to Coal Island in Fiordland off the southern coast of the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

. Between these locations are numerous populations on islands in the Marlborough Sounds. On islands, it is usually found on New Zealand flax/harakeke ('' Phormium tenax''). It is restricted to rodent-free islands and alpine areas. In the Tararua Range and on islands in Dusky Sound it lives on mountain flax/wharariki ('' Phormium colensoi).'' All life cycle stages are found on or near flax.

Behaviour and host species

Adults are nocturnal and hide among the dead flax leaves at the base of a plant during the day, emerging at night to feed. Their feeding damage is smooth ovoid notching of the leaf edges; the asymmetrical notches are fibrous and rough, unlike the smooth notches left by the flax notch caterpillar '' Tmetolophota steropastis''. Eggs are deposited at the bases of leaves. Larvae feed by burrowing into flax roots. If disturbed at night, flax weevils characteristically drop from flax leaves onto the ground or stay motionless on leaves.

Life cycle

White eggs are laid at the base of flax plants. These eggs can take from 3 to 5 weeks to develop into larvae. They gradually darken to a black colour prior to the larvae emerging. The yellow larvae move towards the fan of leaves near the plant base, where they tunnel into the soft tissue within. The timing of the larval or pupal stages are unknown. Adult flax weevils have lived for over 12 months in captivity.

Conservation and threats

The flax weevil is legally protected under Schedule 7 of the 1953 Wildlife Act, making it an offence to collect, possess or harm a specimen. Predation by rats and mice has caused a restriction of their range to predator-free islands and alpine areas; historically, their range was throughout New Zealand. Translocations have occurred to islands, once rodents have been removed. These include Breaksea Island in Fiordland, Titi Island in the Marlborough Sounds, and Mana Island off the south-west coast of the North Island.

Research

Damage to flax plants is usually minimal, but on Mana Island the translocated population has caused the collapse and death of flax plants around the release site. The flax plants on Mana Island are being studied to see if they are more susceptible to flax weevil browsing, with field trials of flax plantings from different sources. The absence of the fungus '' Beauveria'' was suggested as a reason for the lack of bio-control of flax weevils on Mana, but this entomopathogenic fungus turns out to be already present on the island.

References

External links

*Flax weevils discussed on

RNZ Radio New Zealand ( mi, Te Reo Irirangi o Aotearoa), commonly known as Radio NZ or simply RNZ, is a New Zealand public-service radio broadcaster and Crown entity that was established under the Radio New Zealand Act 1995. It operates news and cu ...

'' Critter of the Week''
29 March 2019
{{Taxonbar, from=Q16982060 Endemic fauna of New Zealand Beetles of New Zealand Cyclominae Beetles described in 1932 Endemic insects of New Zealand