Destroying wasp nests — continued

Waimarino Bulletin, Volume 2, Issue 27, 3 December 1984, Page 8

Destroying wasp nests — continued

In this third and final instalment about the wasp menace the Waimarino Bulletin describes further control measures, uses of poison bait etc. Nests in roofs and basements: Methods of wiping out nests include: • Where nests are readily accessible: Use a "borer bomb". Simply place the "bomb" in a tin ( to reduce fire risk), place near the nests in the evening and ignite. Notify the fire brigade to prevent false alarms. • Where nests are not readily accessible: Make an applicator from a can with a removable lid such as a milk powder or baking powder tin. Fit a length of pipe into the lid. This fitting should be tight to prevent wastage of insecticide smoke. Use the older rubberised type of hose or length of metal piping, as plastic hose pipes can melt. Tape a wooden handle to the can. Place a smoke generator into the can, light it, tightly replace the lid and put the nozzle into the hole. Hold the apparatus by the wooden handle as the tin will become very hot. Where the basement of a house is built with a concrete or brick wall containing ventilation blocks, smoke generators can be used in the container described. Block off all ventilators (other than the one the wasps are using) with damp newspaper to confine the fumes, and put the smoke generator nozzle into the remaining ventilator. Ensure that the cubic capacity of the basement is within the limitations of the smoke generator.

When the construction of the basement allows too much ventilation and makes a smoke' generator impracticable, the nest must be sprayed until it is thoroughly saturated with insecticide solution. Chlordane, carbaryl or maldison are suitable for this. Either of the Boracure aerosol insecticides should also prove suitable. (Fly sprays are usually ineffective because of their poor residual action). Sometimes all these methods may fail for no apparent reason. If this does happen, the only consolation is that the nest will usually die over the winter, and that next season's nests will be built in another place. Nests in walls: If the wasps are entering a wall through a small hole several methods can be used to destroy the nest. • Cut off about 100mm of a hose which can fit in the hole. Pack powdered insecticide into it and tape the hose until the powder has compacted to one side. Place the hose in the hole. Wasps must then walk over the insecticide to gain access to their nest. Other possible exits must be blocked. • Blow insecticide in. Pack one end of a suitable length of garden hose with about 50g (2 tablespoons) of insecticide. Place the end with the powder in the entrance to the nest, the other end in the mouth, and then blow sharply (Fig. 5). • Pour several tablespoonsful of liquid insecticide into the hole, or paint the liquid around the entrance so the wasps have to^walk through it to reach the nest. • If the nest is close to the entrance hole, cut sections

off a yellow dichlorvos pest strip and insert them into the hole. The strip slowly releases insecticide fumes that will eventually destroy the wasps. • Use a smoke generator in. the applicator described above. Bore a hole through the wall near the nest, taking care that structural timbers are not between the nest and the hole. Plug the hole with newspaper or grass immediately the drill is withdrawn to prevent wasps escaping. Light the smoke generator, remove the plug and insert the nozzle of the applicator. Use this method in the evening. In all cases, make sure alternative holesare blocked. Nests in the open: In the evening, thoroughly soak exposed nests with concentrated insecticide solutions.

Where the fire risk is not high, petrol, diesel or kerosene may be used. Do not set fire to the nest (it is the fumes which kill the wasps). After the wasps are dead move the nest to a safe place and burn it. Poison Bait This can be used in an apiary if wasps are numerous. Mirex is the only insecticide available for mixing with bait, as others usually repel wasps. Following the instructions, mix the powder with a protein bait (such as fish), and put it out for the wasps in a bait station. This should be located where it cannot be interfered with by children or household pets. Used teartop drink cans are suitable for this purpose. cont'd next page

cont'd from previous page If wasps are feeding on carbohydrates (sweet food) to the exclusion of protein, then Mirex may be mixed with dry icing sugar and placed in a bait station. Provided the mixture is kept dry at all times, honey bees will not be attracted to it. Poison baits give mixed results, mainly because each wasp forages individually and does not communicate the location of a food source as does the honey bee. Shifting Hives If destroying nests around the apiary does not reduce wasp numbers, then it is best to move the hives to another site for the winter. Insecticides Powders: Carbaryl, maldison (Malathion), and lindane are available in powdered form at most hardware or garden shops. Many of the flea powders on the market for treating dogs, pigs and cattle contain enough insecticide to be effective. The multi-purpose insecticide/ fungicide preparations used for spraying fruit trees may also be suitable. Liquids: Most powdered insecticides can be made up into solutions. Some insecticides can be purchased as a liquid concentrate, e.g. maldison (Malathion), dichlorvos, lindane, and pyrethroids (e.g. permethrin, bioresmethrin, fenvalerate). Smoke generators: Borer bombs can be bought from hardware stores.

Pest strips: Dichlorvos (Vapona) strips are available from hardware or grocery stores, and some service stations. Aerosols: Many home garden aerosol insecticides and residual insect sprays are useful for killing wasps. Ordinary fly sprays are usually ineffective. Disclaimer Use of trade names does not imply recommendation by MAF or endorsement in preference to other products not mentioned.