Asian paper wasp
Vespidae - Polistes chinensis
BioSecurity

What does it look like?

Paper wasps are longer and more slender than common and German wasps. Also, unlike common and German wasps, when paper wasps fly they do not hold their legs close to their body. Seeing a wasp flying with "long dangly legs" identifies it as a paper wasp. Males are smaller and more yellow than females. Both Asian and Australian paper wasps build small nests out of regurgitated woody material, which are generally the size of a pear. Other distinctive features of paper wasp nests include:

  • Does not have an outer covering (i.e. you can see into the cells unlike Vespulid nests where the layers of cells are enclosed in an envelope)
  • Roof is covered in a shiny secretion that acts as water-proofing
  • Nests hang from small shrubs and trees, fences, walls, and often under the eaves of houses

Why is it a problem?

Wasps are a major problem in some beech forests where they consume massive amounts of honeydew. Honeydew is produced by a native scale insect and is an important food for native birds, bats, insects and lizards. Wasps also eat huge numbers of native insects and have even been seen killing newly hatched birds. By eating so much, they upset the natural food chain of the forest.

In some beech forests there are an estimated 12 nests, or 10,000 worker wasps, per hectare. This makes the numbers of wasps in these areas higher than that of all native birds, stoats and rodents, put together. Landcare Research (external site) provide further information on the impacts of these wasps.

Wasps are also a nuisance to forestry gangs, and a worry to tourist operators. They are unwelcome guests at summer picnics and barbecues. No-one finds a wasp sting a fun experience. The venom from a wasp sting contains several toxins that can cause a hypersensitive or allergic reaction in some people. Landcare Research (external site) provide detailed first aid advice.

 

Control Methods

There are a range of insecticides available from hardware and garden stores. These include Wasp Killer Dust and Permex Insect Dust, which have permethrin as the active ingredient, and Rentokil Wasp Killer and No Wasps Insecticidal Dust, which both use carbaryl. Follow the safety instructions supplied with the insecticide.

The best way to reduce a local wasp population is to find and destroy all the nests in the area. Usually wasps fly no further than 200 metres. If you search on sunny days, near dawn or dusk, the low light angles will highlight the flight path as wasps enter and leave the nest.

Once a nest has been located, place a dessert spoonful of insecticide at the nest entrance after dark when the wasps have stopped flying. You can use a puffer bottle for this job. Worker wasps flying in and out will spread the powder into the nest and the colony usually dies within a day. If activity continues repeat the treatment until wasp activity ceases. Don't shine your torch into the nest or wasps will fly up the beam.

Alternatively, a targeted wasp bait is available from Nelson-based company Merchento. The bait, Vespex, was developed in conjunction with DOC, although we do not supply it. To purchase the bait contact Merchento. You will have to pass their online test before purchasing.

Note that Vespex may be used on public or private land, but members of the public wishing to carry out wasp control operations on public conservation land need to follow DOC's pesticide permission process.

 

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