Wasps - their impact in New Zealand
New Zealand has some of the highest densities of social wasps in the world. Their natural enemies are not present here, winters are mild, and there is an abundance of food for which they can out-compete our native insects and birds.
Environmental impacts
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The average density of wasp nests in a beech forest that has honeydew is about 12 nests per hectare, which equates to about 10, 000 workers per hectare. In some areas the number of nests has been as high as 50 - 60 nests per hectare, the equivalent of 25 - 30 nests in an area the size of a football field. We estimate that in beech forest with honeydew, the biomass of social wasps (about 1100 g/ha/yr) is greater than that of all the native birds plus stoats and rodents put together. All those wasps eat huge numbers of native insects and consume large quantities of sugary honeydew. By eating so much, wasps upset the natural food chain of the forest. For more information check our Wasp Impacts - Research |
Economic impacts
Wasps bring a financial burden with them too. Beekeepers place hives near areas with honeydew to produce a strong-flavoured honey, particularly popular with the European market. However, when wasps are around, honey production is reduced because there is not much honeydew, and the bees stay home to conserve energy and to protect the hive from raiding wasps. Wasp raids also reduce honey production in non-honeydew areas.
Forestry is affected when logging gangs try to work in areas with lots of wasps. Heavy machinery and angry wasps are not a good mix!
Wasps are attracted to sweet fruit, which can be a headache especially for grape growers. Wasps also like to scavenge on fish so they can be a problem for people fishing close to shore.
The tourist industry also suffers as both domestic and international visitors reduce the time they spend at sites where wasps are a problem.
Social impacts
The results of a questionnaire asking people to rank a range of pest species indicated that New Zealanders generally consider wasps to be a major pest. The risk of being stung appears to be the main reason. The sting is painful at best, and life-threatening at worst. A small proportion of the population will have a severe allergic reaction (called anaphylactic shock), which can be fatal unless treated promptly — about two people die from wasp or bee stings every 3 years. The more common reaction is localised swelling around the sting site which can be uncomfortable and itchy for a number of days.There are also health costs associated with stings. A survey in Auckland recorded that an estimated 850 people sought medical attention for wasp stings in 1992 - 93. Costs of visits to doctors and prescription charges were estimated to be between $33 900 and $35 500 in 1991- 92. In some areas, schools have had to close because of the risk of children being stung while eating their lunch or playing outside. People's enjoyment and safety outdoors can be greatly diminished by wasps.
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Wasp stings |
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Tips to Avoid Being Stung |
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First Aid |