The battle to control wasp numbers in the infested Tasman District in the north of the South Island has had a setback this year.
A new poisoning method using catfood and poison has proved unsuccessful and far fewer wasps have been killed than was hoped.
The coordinator of the Rotoiti Nature Recovery Project, Dave Butler, said the unsuccessful poisoning method had been blamed for a large decline in the number of wasp kills at Lake Rotoiti in the Tasman.
He said the programme had been a great success over the past three years and the overall number of wasps in the area had dropped dramatically.
This has meant the honeydew and insects have been able to thrive, providing food for native birdlife.
There has been a striking number of native birds, such as bellbirds, kaka and parakeets, returning to the area recently.
The poisoning programme, run in the low-lying 300ha of the 825ha "mainland island" nature recovery area, achieved a 55 per cent reduction in the wasp population, compared with 99.87 per cent last year and 74 per cent in 1998.
Mr Butler said the new canned bait consisting of cat food and fipronil poison proved unattractive to the wasps.
He also said trial grids of 200m by 200m, used over half the 300ha block, were proving to be less effective than the old 50m by 100m grid pattern.
NZPA
Catfood lure fails to tempt heavy wasp population
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