Wasps

Wasps are social insects that live in colonies with as many as 5000 wasps per nest. New Zealand has several kinds of native wasps which have evolved here and have never become a nuisance. But five social species of wasps have been accidentally introduced since the 1940s and are classed as pests (German and common wasps, and three species of paper wasps). Introduced wasps are a significant pest which harm our native birds and insects and are a threat to human health and recreation. All social wasps are capable of producing a painful sting but none leave the stinger embedded, as do honey bee workers. Most stings occur

when the colony is accidentally disturbed.

 

Identification

German and common wasps

 

New Zealand has some of the highest densities of German and common wasps (also called as yellowjackets) in the world. This is because they have no natural predators here, the winters are mild and there is plenty of food for them.

Introduced German and common social wasps (Vespula spp.) are very similar in appearance.

  • Vespula spp.range from 3/8″ to 5/8″ long.
  • They are bright yellow with black lines, spots, triangles or diamonds on their abdomen (different species have different colour patterns).
  • Yellowjackets have a hard and shiny body with few hairs.
  • Wings fold into a narrow strip on top of the abdomen when they are at rest.
  • They can be mistaken for honeybees, but they lack the hairy body and are more intensely coloured.

 

Difference between German and common wasp appearance

The German and common wasps are similar in many ways. The only difference is in the markings on their abdomens. The German wasp usually has separate black dots while the common wasp’s dots are usually fused to its black rings. The common wasp also has a longer black stripe down the centre of its face, shaped like an anchor.

Common Wasp¹ (Vespa vulgaris)- Black dots and rings on the abdomen which are usually fused. German Wasp² (V. germanica)- Black dots on the abdomen, which are usually (but not always) separate from the black rings.

Common and German wasp nests

Their nests are different, too. German wasp nests are grey-coloured, made from live wood. Common wasp nests are brown-coloured and made from dead or rotten wood. They commonly build their nests underground or in banks but will settle for anywhere that is warm and dry, like attics, house roofs, eaves, and walls. The nest entrance is small and inconspicuous. Colonies are readily defended, and wasps will sting when the nests or nest area is disturbed.

 

Paper wasps (Polistes spp.)

Although not as much of a problem as German and common wasps, paper wasps (Asian, European and Australian) have also been introduced to New Zealand. The Asian paper wasp has been found in the North Island and top of the South Island. The Australian paper wasp remains confined to the north of the North Island. Both paper wasps build small nests out of regurgitated woody material, about the size of a pear.

  • Paper wasps are slender with long legs (1/2 to 1 inch long) that dangle beneath their bodies when they fly.
  • Generally brown with yellowish markings.
  • European paper wasps are black and yellow in colour and resemble yellow jackets.
Asian paper wasp³ European paper wasp Australian paper wasp

 

 

Paper wasp nest

Paper wasps build their nests with a papery pulp. They construct only one comb of cells without any protective envelope. They build nests under any horizontal surface and are commonly found on limbs, overhangs, building eaves, beams and supports in attics, garages, barns, sheds and similar places.

Paper wasp nests are generally small and may have less than a dozen individuals. At most, about 100 wasps may be found in a nest. Like German and common wasps, paper wasps do not reuse nests the following year.

A small paper wasp nest

What do they eat?

  • They capture insects (including caterpillars, flies and crickets) and spiders to feed their larvae
  • Adults feed on sugar such as the juices of ripening and overripe fruits and honeydew (a sugary substance secreted by certain insects, like aphids, hoppers, white flies).
  • Paper wasps also feed on the nectar of flowers.
  • During late summer and fall, some wasps (mainly common and German wasps) become aggressive scavengers around human food and can be common in outdoors where food or drinks are available.

 

Preventing wasps and their nests build up

Prevention is always better than cure. There are things you can do to stop wasps invading your home or business.

  1. Keeping Windows and doors shut- Simply keeping your home secure will stop wasps wandering into the house.
  2. Keep your bins shut- Open bins will attract greedy wasps looking for a cheap, sweet meal. Keep you bins away from the house and make sure the lid is on properly.
  3. Check for nests early-You can check all the most likely spots of wasps each spring when the nests are tiny and easy to deal with. They will be about the size of a golf ball. Check the loft, garage, shed and under eaves if you see any wasps flying around to make sure you haven’t got any tiny wee nest anywhere on your property.
  4. Many concerns with social wasps occur late in the season when colonies grow large and the above-ground nests of German and common and paper wasps become apparent. If the wasps are not causing a problem, the best solution is to wait until the nest is abandoned in the fall. The nest can be safely removed in the winter or, if left alone, will break up during late fall and winter.

 

Common and German wasp Control methods

  1. Active wasps causing problems can be managed by using wasp traps filled with a lure that attracts the adult wasps and catch them. The wasps get entrapped and slowly drowns and die in the lure. Once the traps are full wasps or no lure is left, then empty the traps and re-fill them with fresh lure ensuring no spill of lure on the outside of the traps*.
  2. Wasp bait is also an effective way of treating wasp nests. Hawkeye wasp bait is a protein and sugar- based bait, containing the insecticide indoxacarb, which is deployed from a bait station. The adult wasps take the bait back to their nests to feed their young ones, wiping out the nest. This bait has been scientifically developed and tested on the wasp larvae for the palatability in the laboratory. Hawkeye wasp bait is not attractive to bees.
  3. If the population of wasps is/suddenly rises to a very high level then use a combination of Hawkeye wasp lure and wasp bait for a quick knock- down. This combo works very well in knocking the population levels quickly as the Hawkeye wasp lure traps highly active sugar source seeking wasps and the bait controls the overall population of the nest as it is taken back to the nests by the foragers looking for protein source for their young ones.
  4. The above methods are necessary when you do not know the wasp nest location. When the nest location is known it can be destroyed with an insecticide. Contact your local pest controller for the wasp nest extermination via insecticide application. A professional pest controller has the technical knowledge and access to a range of professional use insecticides which are not available to the public. They’ll also have the appropriate protective equipment to avoid getting a nasty sting. A pest controller will normally apply an insecticide near the entrance of the nest made during late evening or cool periods in early morning, when the wasps do not readily fly, and most foragers have returned to the colony. The wasps then bring the chemical into the nest. After a couple of days the wasps will die from the dose of the insecticide.

 

Paper wasp control methods

Reducing paper wasps nesting sites is possible before the colonies become established in early spring. This is done by sealing all openings that allow access to hollow tubing or similar materials or removing the exposed nests at an early stage when they are only 5-6 cell sized with only queen or few worker wasps. For exposed paper wasp nests, insecticides can easily be applied directly to the nest at the dusk or early morning when the wasps are not very active and are still in/on the nests.

* NOTE: Wasp lure spills on the outside of the traps can attract bees especially during the end of the season when there are not many flowers around or after honey harvesting in apiaries.

 

Quick facts

  • Wasps commonly nest in a wide variety of sites, including on and inside buildings, in trees and in the ground.
  • Wasps will generally not bother people when their nests are not near human activity.
  • When wasp nests occur close to where people are active, the nests should be eliminated to minimize the risk of stings. And when you don’t know where the nests are then using a bait or lure trap is the best way to get rid of the wasps
  • Queens are the only members of the colony that survive the winter.
  • Newly produced and mated queens leave their old nests and search for protected sites to spend the winter (under loose tree bark, old rotten stumps, or within buildings, such as under siding).

 

Wasp sting

Social wasps sting to defend them or their colony. Some wasps can also become aggressive during late summer and fall and may sting unprovoked.

Most people have only minor reactions to wasp stings, but a few may experience more serious allergic reactions.

 

Treating wasp stings

If after a sting you have difficulties breathing, dizziness or a swollen face – you need to seek immediate medical treatment.

If you’ve not had a severe allergic reaction, your sting will still be very painful.

 

To treat a sting yourself:
  1. Wash around the sting with soap and water
  2. Apply a cold compress, like an ice pack, for at least 10 minutes
  3. Elevate the affected area, if possible.

Avoid scratching and don’t try any daft home remedies. Vinegar and bicarbonate of soda is probably going to make it worse!

Photo attributions

¹ Common wasp: soebe / CC BY-SA
² German wasp: Fir0002/Flagstaffotos / GFDL v1.2
³ Asian paper wasp: Daiju Azuma (Opencage) / CC BY
European paper wasp: Alvesgaspar / CC BY-SA
Australian paper wasp: © Tom / CC BY 4.0
Paper wasp nest: © David Whyte / CC BY-SA 4.0

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