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An evaluation of the costs of pest wasps (Vespula species) in New Zealand (PDF, 1,280K)

Summary

This report estimates that introduced wasps cost New Zealand’s economy more than $130 million dollars a year, with the biggest economic impacts on farming, beekeeping, horticulture and forestry workers. 

This assessment was based on a literature review. Information was collected from previous studies and from affected sectors in New Zealand to estimate the total costs of wasps, ie the costs that could be avoided and the opportunities that could be gained if wasps were not present in New Zealand.

New Zealand has some of the highest densities of German and common wasps in the world. Wasps have huge social and biological impacts; they are one of the most damaging invertebrate pests in New Zealand, harming our native birds and insects.

This study found that wasps also have a major financial impact on primary industries and the health sector. This includes:

• more than $60 million a year in costs to pastoral farming from wasps disrupting bee pollination activities, reducing the amount of clover in pastures and increasing fertiliser costs.
• almost $9 million a year cost to beekeepers from wasps attacking honey bees, robbing their honey and destroying hives.
• wasp-related traffic accidents estimated to cost $1.4 million a year.
• over $1 million each year spent on health costs from wasp stings.
• on top of the direct costs, almost $60 million a year is lost in unrealised honey production from beech forest honeydew which is currently being monopolised by wasps. Honeydew is also a valuable energy source for kaka, tui and bellbirds.