Wasp Behaviour

At the beginning of a season the nest has low numbers of wasps and tries to

build up numbers quickly, mainly by feeding on protein. This is the best

time to use meat based poisons in traps, such as Fipronil.

From about Veraison onwards, the nest switches over from a protein diet to a

carbohydrate diet. This is when they will attack grapes. There is no certified

poison to be used with sugars, as it would also harm beneficial insects,

particularly bees.

At this point the only method of control is to locate the nest and destroy it

with a non selective powder insecticide such as carbaryl, at dusk.

European Wasps are Not Cool

1P. Smart , 2R.G. Dambergs

1 Pressing Matters, PO Box 2119, Lower Sandy Bay, TAS 7000, Australia. 2 The Australian Wine Research Institute, Tasmanian Institute of Agricultural Research, Private Bag 98, Hobart, TAS 7001, Australia

Abstract

European Wasp, Vespula germanica, first reached Australia in 1956 with the first Australian recorded sighting in Tasmania. Since then it can now be found in every cool

and wet site in Australia. The European Wasp can cause significant damage to vineyards, not just from a crop loss aspect, but also with respect to quality. The method of

attacking fruit is to puncture the berry and feed on the flesh which can result in off flavours and moulds growing. The 2011 season at Pressing Matters resulted in severe

European Wasp pressure with significant damage. Once wasps are found eating fruit it is too late to trap with meat based poisons, as they have already switched from a

protein diet to a carbohydrate diet. During this period the only effective method is to locate nests and destroy them, and many novel methods of location were

implemented. It was found that while wasps fly in straight lines, they may also have visual way-points and turn by up to 45 degrees.

Damage

Wasp damage is easy to differentiate from

bird damage, as the wasp will pierce a hole

and eat the flesh of the berry. This will

leave the skin intact and sometimes, the

seeds will hang from some of the vascular

bundles.

. These photos are examples of the damage

that was found in the 2011 season

Method of Locating a Nest

1. Start at the food source (vineyard) and look in the general direction they are coming from/travelling too.

What you are looking for is a “Line” or “Highway”

2. Once a line is confirmed by several wasps, one persons walks about 50m in front, along the direction of

travel.

3. Once they confirm that they are on the line, everyone moves forward about 50m.

4. This continues until the nest is found. If the line is lost, work backwards to the last location they were seen.

5. The Wasp Highway can turn by up to 45°, and the wasps use visual waypoints such as a depression in the

forest, a fence line, a tree line, in between vineyard blocks etc.

6. Within 20m of the nest, the numbers of wasps will increase and will be travelling different, confusing

directions. This is when you stop looking up and start looking down.

7. Wasps nest are holes in the ground, not more than a couple of centimetres across. It is easy to find the

entering/exiting wasps than the hole itself.

Aerial map of the 20 nests found during the 2011

season at Pressing Matters. The greatest distance

travelled by a wasp from the edge of the vineyard to

the nest was 600m.

This is a picture of a wasp nest with several

entering and exiting. This was a very large nest,

probably built up over several seasons.

This picture shows a path travelled by the wasps.

From the corner of the vineyard they headed for a tall

tree, then turned right and followed a track up to their

nest.

Wasp Attractant Trial

A trial was undertaken of two commercially available

wasp attractants: European Wasp Attractant (powder)

by Evergreen Marketing and Liquid Wasp Attractant

by Agrisense. The first is a powder which activates in

24 hours and smells yeasty. The liquid smells like

ethyl acetate.

The powder stank of dirty nappies after a few days

and was ineffective. The liquid was very effective as

the picture on the right shows. This could be used

with meat traps, as long as the wasps are not caught.

The tools required:

•2 people

•Sun protection

•Polarised sunglasses

•GPS or mobile

phone

•Surveyor marking

tape

•Epi-pen or anti

histamine tablets