Flying squad takes over in beetle battle against ragwort
ragwort plume moth
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The wild West Coast is one of the last frontiers for ragwort – but a flying squad of new insects is being sent in this
week, in the hope it can destroy the noxious weed once and for all.
Ragwort (Senecio jacobaea) replaces pasture and contains toxins that can cause fatal liver damage to cattle, horses,
goats and even deer. It reduces butterfat, milk and meat production, and can taint the flavour of milk, meat and even
honey.
An arsenal of insects, most notably the ragwort flea beetle, has largely won the battle in most parts of the country.
But the beetle has failed to thrive in areas of high rainfall and intensive dairying such as the West Coast, Southland,
and Otago.
At high noon on Friday, about 300 ragwort plume moths and ragwort crown-boring moths will be released onto a farm at
Inchbonnie, near Jacksons on the Arthur’s Pass. It is hoped that these moths will perform well and go on to be used in
other ragwort-plagued parts of the country.
The release is the culmination of three years work by the West Coast Ragwort Control Trust, who will continue to rear
and release the insects on the West Coast.
Landcare Research identified the two insects as being potentially useful, ensured that they would eat only ragwort, and
reared the insects for initial release. Landcare Research plans to begin a national rearing and release programme in
conjunction with regional councils in other ragwort-affected parts of the country.
Landcare Research weed researcher Hugh Gourlay says the plume moth in particular has almost wiped out ragwort in
Tasmania and Victoria, in similar climates to the West Coast.
“The plume moth attacks the roots and kills plants, while the crown-boring moth attacks both leaves and roots, reducing
plant growth and seed production.
“Both insects have several generations in one year, so chances are high that they will establish and thrive.
“Both moths are specific to ragwort – in other words, they are unlikely to eat anything else.”
The moths will be released at Inchbonnie (west of Jacksons, south of Lake Brunner) at 12pm, Friday the 17th of March.
Contact Hugh Gourlay for directions.
ENDS