A pesticide treatment program is designed to get rid of pests by using one or more pesticides. Pesticides should not be used unless there is a definite need to do so and where a pest problem has been identified, such as extensive cockroach infestations in people’s houses.
Before a pesticide application program is undertaken, alternative methods of pest control must be considered, such as domestic hygiene measures.
In applying a pesticide it is extremely important to choose the correct one for the job and to apply it safely and in accordance with the label directions.
8.1 Choosing the correct pesticideIn choosing the correct pesticide for a treatment program there are a number of factors that should be considered:
- Which of the available pesticides will control the target pest or pests?
- Of these, which would be the better pesticide to use? The choice should take into account the required application method and the pesticide's level of toxicity.
- How is it applied?
- For how long will it control the pest?
- How toxic is it to humans and other non-target species?
- Can it cause damage to the environment and how might this occur?
- Is it biodegradable?
- How much pesticide is required for the job?
All of these questions need to be considered carefully before the final choice of pesticide is made. If for some reason there is not enough information supplied with the product to answer all the questions, it is important to get this information before buying or using the pesticide from the people who sell it.
If there is any doubt about any aspect of pesticide use, check with an EHO at your local government. It may also be possible to contact the manufacturer directly.
Once the pesticide has been chosen, there are a number of questions which need to be answered in relation to the pesticide itself, the equipment and the application method. These are outlined below.
- How much of the job will one container of pesticide do? Will more be needed and if so, how much? Does it need to be mixed with anything? If so, what and how much?
- Where and how should it be stored?
- How should containers and leftover pesticide be disposed of?
- What application equipment is needed?
- What protective clothing and equipment is required?
- How should the protective clothing and equipment, and the application equipment be cleaned?
The application method
- What warnings are given?
- What safety measures are necessary while the pesticide is being used?
- How must the pesticide be applied?
8.2 Insecticide typesMost of the pesticides used around houses are insecticides. They are used to kill the many insect pests that annoy people and/or affect their health. The majority of insecticides belong to several basic groups which are broadly defined by the chemicals used to make them. These are inorganic insecticides, organic pyrethrins, synthetic pyrethroids, organophosphorous insecticides and insect growth regulators.
Inorganic insecticidesThese insecticides are of mineral origin and include substances such as arsenic trioxide powder (used in termite treatments) and boric acid (used in cockroach treatments). Some of them are not commonly used these days. This is because they are often highly toxic to mammals (furred, warm-blloded animals), are non-biodegradable, or simply because easier methods have been found.
Most inorganic pesticides have a stomach poisoning action. For this reason they are usually in solid form and are applied as baits.
Organic pyrethrinsThese are made from certain plants. The most widely used natural insecticide is pyrethrin which is obtained from a type of chrysanthemum flower.
Pyrethrin has a number of advantages as an insecticide:
- It is a broad spectrum insecticide. This means it will kill a wide range of insect pests.
- It has low toxicity to mammals
- It acts quickly, that is, it has a fast knockdown
- It is biodegradable (breaks down fairly quickly)
Synthetic pyrethroidsThis is a group of synthetic insecticides. This means they are insecticides which have been chemically manufactured (man-made) to work like naturally occurring pyrethrins. This group of chemicals are generally low in toxicity to humans, but are very effective against a wide variety of insect pests.
Examples of synthetic pyrethroids are:
- Coopex, Cislin, Crackdown and Biflex are four commercial products in this group.
Fig 5.27: Synthetic Pyrethroid
Organochlorine insecticidesThese are synthetic organic compounds which contain chlorine. They include substances such as DDT, dieldrin, chlordane, heptachlor and endosulphan.
Organochlorines are mainly used as contact and oral poisons which act on the nervous system. Because of their persistence in and impact on the environment, organochlorines are no longer used to treat pests in or around buildings.
Only one organochlorine is currently registered and it is used only in agriculture under permit. All other organchlorines were deregistered for use in Australia in 1996.
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Organophosphorus insecticidesThese are synthetic organic pesticides which are manufactured from carbon chemicals and also contain phosphorus. They include chlorpyrifos, dichlorvos, malathion, diazinon and temephos.
Some pesticides in this group are very toxic to mammals, such as people, kangaroos and dogs, and other animals such as bees and fish. Their use is restricted to prevent exposure to non-target species.
Organophosphates tend to break down in the environment more rapidly than organochlorines but some of them do remain active for months or years. A number of organophosphate insecticides have been developed for the control of common household pests, for example: termites, flies, cockroaches, mosquitoes, and spiders. Some organophosphates contain solvents and can have a strong chemical odour. Some people object to this odour and as a consequence prefer only odourless pesticides be used around or in their homes.
Carbamate insecticidesThese are manufactured compounds that are relatively unstable. That is, they usually break down in the environment within weeks or months. One of the most common carbamates is propoxur which is the active chemical in the product Baygon.
Carbamate insecticides act mainly as contact and oral poisons and are used as surface sprays or baits to control household pests.
8.3 Insecticide applicationsInsecticides are applied (used) in one of the following ways:
- Surface spraying for the control of crawling insects
- Space spraying for the control of flying insects
- As baits, powders, dusts and granules for the control of crawling insects
- As fumigation treatments for the control of insects inside materials, such as timber, stored grain
Surface sprayingSurface spraying with insecticides can include spraying floors, skirting boards, under benches, inside cupboards, outside walls, around the yard and at the rubbish tip. The insecticide is often applied as a liquid spray or paint so that the surface is effectively covered with the substance.
Liquid insecticides are usually dispensed (released) from some form of hand operated pressurised sprayer. There are a number of different sprayers, which are discussed below.
Aerosol canThe insecticide and a propellant are contained in one can. Examples are products like Baygon and Mortein. This is an easy and convenient method of killing small numbers of flying or crawling insects, but is usually expensive. Aerosol cans should be used only for small areas and are effective knock-down pesticides.
Fig. 5.28: Using an aerosol surface spray. Picture of a pressurised can
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Pressurised (compressed air) sprayerThis sprayer, also called a hand pump sprayer, contains:
- a tank to hold the insecticide
- a plunger assembly to pump air into the tank and thus create pressure inside the tank
- a hose to deliver the insecticide from the tank
- a nozzle (or gun) from which the insecticide is sprayed. The nozzle also has some kind of tap to control the flow of insecticide. There are several types of nozzle which produce different spray shapes such as wide sprays for foundations or pin point sprays for cracks and crevices in cupboards.
Compressed air sprayers can be made of stainless steel or of strong plastic.
Fig 5.29: Compressed air sprayers
Steps to take before mixing and applying pesticides
Prior to mixing any pesticide, ensure all equipment is checked and repaired where found to be faulty.
Note: Before checking and or filling spray equipment put on personnel protective equipment (PPE) and where necessary wash the spray equipment.
To fill the sprayer with insecticide, first read the label and put on any additional personal protective equipment required.
Before the plunger assembly is unscrewed from the sprayer, release the pressure relief valve, this is usually located towards the top of the sprayer, then carefully unscrew the plunger.
Note: Sometimes there will still be some air left in the sprayer even though the pressure relief valve has been activated, so take care when removing the plunger as pesticide residue may escape and could contaminate hands and eyes.
Place a small quantity of clean water in the sprayer, this will assist in the mixing process. It will also reduce the likelihood of the operator being splashed with undiluted pesticide when pouring the pesticide into the sprayer.
Carefully read the label for the amount of pesticide required to treat the pest and place the appropriate amount of pesticide into a measuring jug, then carefully pour it into the sprayer.
Next, slowly add the required amount of water to the sprayer in accordance with the label, being mindful of the capacity of the sprayer and careful not to overfill the sprayer.
After the sprayer has been filled, screw the plunger on tightly. If there is an adjustable nozzle on the end of the lance, check to make sure it is off and the handle or plunger (depending on the type of sprayer) is used to pump up the pressure. When enough pressure is produced (usually about 10 - 20 pumps) the sprayer is ready for use.
A number of precautions should be remembered while using the sprayer and applying the insecticide:
- The trigger on the lance or the nozzle tap should not be turned on or activated unless the lance is pointed at the area to be sprayed.
- Care should be taken to make sure that spray does not drift onto the operator or anywhere it is not intended. If weather conditions deteriorate and it becomes windy, spraying should cease or be delayed. Even in low wind, wind direction must be noted and action taken to reduce the effect of any spray drift.
If appropriate, a nozzle hood can be fitted to the sprayer to reduce spray drift. These are often used with herbicides.
- The spraying area should be cleared of other people, pets and food bowls while the insecticide is applied.
Note: Fish and birds are very susceptible to pesticide poisoning, so great care must be taken not to allow spray drift to contaminate them or their food.
- The operator must be wearing the correct protective clothing and equipment during the whole spraying operation.
- Spraying should be carried out in the cool times of the day
- The operator must be upwind of spray drift, if any, and must not smoke or eat while applying the insecticide
At mealtimes and tea-breaks, the operator must wash their hands and face with soap and cool to warm water (i.e. not hot water) and remove aprons and gloves before eating or smoking
- At the end of the operation the spray equipment must be thoroughly cleaned. Dispose of any pesticide left over and rinse the spray equipment with water. The nozzle and hose are best cleaned by partly filling the tank with clean water, pumping up the pressure and spraying water through the nozzle, ensuring the waste liquid does not create a health hazard or harm to the environment.
Periodically the sprayer should be cleaned with a brush and warm soapy water and any faults repaired.
Motorised back pack sprayerThis sprayer is mounted on the operator's back. Instead of using a hand pump to create pressure inside the tank, a small petrol engine drives a pump which pumps the insecticide to the nozzle which is fitted with a control tap.
It is essential these sprayers are well maintained, as contamination of the user can occur without them knowing. It is not unusual for leaking equipment to be mistaken for sweat, as using this type of equipment is hard work. Therefore, it is essential this equipment is checked regularly.
This type of sprayer is useful for large scale operations. The same precautions for the hand pump sprayer also apply to motorised sprayers.
Fig 5.30: Motorised back pack sprayer
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Large and small capacity power sprayersThis type of sprayer is used by professional pest control operators for medium- to large-volume spraying or continuous spraying. A petrol motor connected to a pump and pesticide emulsion tank is mounted on a trailer, or the back of a ute or truck. Chemical flows are controlled by various taps. Hose reel/s are connected to the pump which to allow large area to be treated without the need to shift the vehicle.
Fig 5.31: Vehicle mounted sprayrig
Smaller battery-powered sprayers which can be mounted on trolleys are available and may be useful in applying pesticides in community situations. Batteries must be kept charged to prolong battery life.
Note: If using lithium batteries on the sprayer, ensure the correct charger is used for charging this type of battery.
Applying pesticides by paint brushA very simple way to apply liquid insecticide is to use a paint brush to spread it over the required surfaces. It is a particularly good method for crack and crevice treatments in food areas, such as kitchen and house cupboards, along skirting boards, and in some types of shops. This method can be used also for small areas which need treatment or when it is important to have no spray drift.
Fig. 5.32: Crack and crevice painting treatment.
8.4 Other pesticide applications
RodenticidesRodenticides used in communities may either be in pellet or solid block form. Great care must be taken in placing these baits, as cats and dogs are known to eat them. These baits must be kept out of the reach of children and should be placed in lockable bait boxes. Where bait boxes are placed outside a building in full view of the public they should be secured at all time.
Fig 5.33: Rodenticide for Rats and Mice
If an EHP needs to use rodenticide baits, check with the EHP supervisor or the Shire EHO before using them.
The label will provide the general precautions (safety rules) and baiting method. The positioning and number of rodenticide baits is particularly important.
It is difficult to guess the number of rodents to be treated, so it may be necessary to use a trial-and-error method. For example, a number of baits are positioned and checked each day to see if they are being eaten away. If all the baits are being taken, the number of baits should be increased to make sure all the rodents are killed.
Baits must be put in places where:
- the mice and rats are known to rest or search for food, such as in cupboards
- they cannot be reached by children or pets
Baits become ineffective when they are wet or covered in dust or soil. Change uneaten baits regularly.
It is also important to remember where the baits have been put, so that any unused baits can be picked up once the program is finished.
Fig 5.34: Bait box for Rats and Mice