Baiting European wasps: whybother?

Merydyn Davison

Insect Inquiries Officer

Orange Agricultural Institute

European wasps

• European wasps likethe same fruits we do.

• They have all day tolocate and eat all theywant.

• They can get toripening fruit beforewe do.

European wasps

• They sting people and interrupt work.

• They kill some insect pests but theyremove many invertebrates from the areaaround the nest, beneficials as well asnon- target species.

• Baiting saves time and effort locating andphysically treating a nest.

European wasps: Timing

There are three perfect periods within theirlife cycle for baiting:

• Unfertilized queens looking for sugars tobuild fat in Summer and Autumn.

• Workers looking for protein to feed larvae,in late spring/ summer.

• Water stress during drought.

European wasps

In late winter / early spring:

• Queens will fly when outside temperaturesare above 12 degrees C but only in thewarmest part of the day.

• A chance to reduce hibernating queensand small primary nests before larvaeprovide enough nutrition for the queen toincrease egg laying.

European wasps

Bait ingredients should suit the life stage ofworkers:

• Unfertilized queens love apples for fat depositionfor hibernation and future egg laying.

• Workers love apples as fuel to power flight forforaging.

• Workers love meat to feed larvae. Meat can onlybe digested by larvae. Meat or liver is best likedas a large chunks.

European wasps

• European wasps have a geneticpredisposition for apple which means baitsare not attractive to other insect pollinatorseg. bees or predatory wasps.

• Wasps will locate bait faster if they are inan area with a bait station.

European wasps

Bait placement:

Workers forage 200 m from the nest but willNOT leave the flight path for at least 20 m.

• Preferred nesting sites are creeks, damsembankments, logs, old rabbit burrows, housesand stored machinery.

• Place stations around these areas through outthe year. Early detection means a problem freepicking season.

European waps

6 to 8 week old nest produces 50 to 100workers weekly. Foraging activities beginto be intensive and intrusive.

Water-seeking behaviour in hot weatheraround watering points can create anxietyin animals and can cause injury.

European wasps

Workers are not good at recruiting others to a food source.They need at least a day for nest mates to find thestation. This means that pre–baiting is very important.

• First place a station free of insecticide dust at thechosen site.

• When more workers visit the site, renew apple or meatand add dust in the evening.

• If wasp numbers are high, place a treated station within2m of the original. Attaching the new station should besafe as it will take the wasps some time to find it.

European wasps

How to make a bait station

Requirements;

• 2 milk cartons

• String or tape for tyingbait to stationary objecteg. tree.

• Apple or meat

• Stanley knife.

European wasps: Bait station

• Measure 2 cm frombase & draw a line ontwo sides of thecarton.

European wasps: Bait station

• Once the first line isdrawn, measure asecond line 5 cm frombase.

• Draw on two sides.

European wasps: Bait station

• Measure a point ½way along the 2 cmline and then on the 5cm line.

• Draw a line from onepoint to the other,within the two lines.

European wasps: Bait station

• Once the internal lineis drawn, measure 1.5cm (½ way point)along the middle line.

• Draw a dotted linefrom edge to edge.

• Measure 1.5 cm ondotted line from midpoint.

European wasps: Bait station

• Draw a line from the1.5cm point on thedotted line to the pointon the 5cm line wherethe middle line meets.

• Complete thediamond on bothsides of the carton.

European waps: Bait station

• Begin to cut out thediamond.

• Complete cut out onthe second side of thecarton.

European wasps: Bait station

• Take second carton:measure 7 cms frombase.

• Draw line on all sides.

European wasps: Bait station

• Cut around line.

• Free standing ½carton.

European wasps: Bait station

• Turn ½ carton on end.

• Dot out the foldinglines on the cartonbase.

• Draw a triangle andcut out on 2 sidesonly.

European waps: Bait station

• On the base, measure2cms from each side ofthe carton.

• Draw lines down to edge.

• Cut out middle section ofcarton on two sides.

European wasps: Bait station

• Freestanding base.

• Open top of carton.

European wasps: Bait station

• Slide free standingbase down intocarton.

European wasps: Bait station

• Slice the bottom offan apple and place onfalse floor.

• Fold down top.

• Once the station issecure, opening thetop to check thequantity of bait left, iseasy!

European wasps

European wasps like to feed 1.5 m above ground. If tyingthe station to a branch, spray the area with a surfacespray as wasps will not feed on anything which has antson it. Ants also like liver, if that is the bait being used.

The separation of dust and bait is very important as waspsdon’t mind walking through anything to get the preferredfood. Mixing dust with bait changes the chemical profileof the bait and is unattractive to wasps.

Once treated workers return to the nest, the colony will diewithin 24 hrs.

This is a simple and time effective way of managing adifficult to detect pest.

European wasps

Unfertilized queens do not follow workerrules. They are capable of flying 5 km insearch of carbohydrates and many queensfrom different nests will happily share fruit.

Home gardeners have reported more than 2thousand queens per tree when there areno other trees in fruit.

European wasps

• Baiting throughout the year, when thetemperature is right for flight, should beeasy, not expensive and be capable ofnipping infestations ‘in the bud’. The baitstation can be a simple detection andelimination tool to ensure european waspsnever reach damaging populations at anytime of the year.