DAMAGE TO FLAX PLANT

Hokitika Guardian, 11 August 1931, Page 5

DAMAGE TO FLAX PLANT

NEW PEST DISCOVERED.

NATIVE AVEEVIL ON D'URVILLE ISLAND.

NELSON, August 9.

A native weevil, hitherto unknown which destroys flax has been discovered on D’Urville jsland, in Cook Strait, kt is the worst 'flax pest known in Lsew Zealand, but it is not likely ,to prove particularly harmful to the flax industry, because, so fair •as is known by the entomologists of the Cawthron

Institute, who have been studying its habits, it is confined to that island, and unlikely to spread unless transported accidentally to the mainland.

Specimens of the. eqlprit, mounted on pins, were shown to a reporter Who visited the institute. They were about an inch long, chocolate' brown in 001-' our, with short,..blunt snouts.

RISK TO FLAX INDUSTRY. Commenting on the importance of the of the insect to the flax industry of |the Dominion, Mr David Miller, chiel entomologist to the institute, said tqat the weevil had considerable powers of destruction, and it was fortunate that it seemed to be restricted to D’Urviiie Island; thus its depredations would be strictly limited so long as he was not transported by accident to the North or South (Islands, The creature—-so fav it lacks a technical name, though several'of its relations are well known—is doubly venomous, because not only do the adults attack the leaves of the flax (Phormium tenax), but the larvae a'-stroy the fans by feeding all around their bases. As a discovery which k not altogether- ‘-welcome to;; \ the jpakgrower, the habits of this- weevil,> = have been studied with great interest by the entomological staff of the institute, ’ and particularly by MrVE. S. Gourlay, , first assistant .entomologist, who has been entrusted with the task of investigating its nature and' habits. ."

.FOUND iix CHANCE. f . (Mr Gourlay explained that the insect was come upon by chance during a recent expedition made by a party to the island. The honour of the discovery lay with Miss R. F. B. Huffam, of Richmond, Nelson, while the host association <(the flax) was discovered by Mr E. Fairburn, of vyhaiigarei. .'lnvestigation carried but on the spot, and that pur-, sued since' in the laboratory -■ had shown that the weevil hid during the daytime among the closely-pile'd*/ leaves ana debris at the base of ‘..the flax bush, coming out to feed shortly after dusk.

Fortunately, added Mr Gourlay, the distribution 5 of the pest was not a matter fori grave concern as the insect could not fly and must thus, rely on the reasonable proximity of - areas of flax for its existence. But the vitality -of the ftdwtt«~waa -rottt«i'ltablej--'4hey-,feeiiig tvblm«» to live ftu’ considerable periods without food. This sugggbsted that, in the event of the destruction by them of one area of flax, a large radius could be coveyeu in their search for other suitable breed- . ' ing grounds, but with the absence o! - 3 j. wings, they could not cross water on their own account. So far as was known these breeding grounds were confined tc the flax areas at .the northern end oi the island where they were first found.Mi-.fi Mr Gourlay went on to explain their breeding habits, /The female laid its , eggs on the flax plant.-.,- Fifty £uch brought to the insectary. of the institute had laid the remarkably good total of 540 in twenty-four hours. The egg" hatched in about three weeks and, as the larvae grew, they began boring into the soft tissue of the flax bowl. The parts eaten became blackened and the tissues. adjacent swollen. To laymen the presence of the weevil would be Indicated by trusses of dead flan being strewn around a bush which had , formerly been quite healthy. coooons were also made of flax. aiK were quite smooth. Mr Gourlay observed that it was no. unusual to . find native insects in iso lated areas. - Several branches of tff genus to ••which this weevil belongeu •were known* in New Zealand.