Choosing and using products

  • Chemical sprays only provide temporary relief of flies
  • Carefully select suitable products and application methods
  • Avoid exposing cattle and feed products to insecticides

What type of fly do you wish to control?

Fly Identification Chart

House flies are often seen resting on fence posts and railings, vegetation, and inside feed processing areas and offices. House flies feed from moist locations on cattle and can be seen around the eyes, nose and mouth, causing tail swishes, ear flicks and head tosses.

Stable flies are mainly seen resting on vertical surfaces such as fence posts and railings and outer building walls. They are also often seen on the sides of white vehicles. Stable flies typically bite the legs and belly areas of cattle causing them to stomp their feet, toss their heads and switch their tails.

Bushflies breed in the dung of pastured cattle and other animals and can fly into feedlots from these breeding sites. They are often seen outside on fence posts and railings, and on vegetation. Bushflies feed from moist secretions on cattle and are usually seen congregating around the eyes, nose and mouth, causing tail swishes, ear flicks and head tosses.

Blowflies are often seen near animal carcasses and cattle composting areas and can often be found feeding on the sugars found in molasses-based feeds. They can be found indoors.

When to treat flies?

Assess fly numbers

House flies have population peaks from late spring to late autumn, especially in the weeks following rainfall. Only apply insecticides when the fly population has reached an unacceptable level and becomes a nuisance to stock and staff.

Stable flies are more often seen in spring and autumn. Treat when you see more than 20 adult stable flies per animal.

Bushflies usually arrive in waves in late spring and late autumn or in other high rainfall periods. Only apply insecticides if the population reaches a level causing annoyance to cattle and staff. Because bush flies breed outside of the feedlot, use of larvicides is not effective.

Blowflies can be found in low numbers at most times and usually cause little annoyance to cattle or staff. Only treat as needed.

Where to treat flies?

House flies

Adult flies – Outside

Treat places where flies rest, e.g. exterior of feed bunks, pen fences, exterior of buildings, underside of shade cloth, trees and other vegetation.

Adult flies – Indoors

Treat areas where flies rest e.g. walls, ceiling, floors, and window sills.

Larvae

Treat major breeding sites, e.g. under pen fence lines, drains, sedimentation pond, hospital area, and areas where spilled feed or other organic matter accumulates.

Stable flies

Adult flies – Outside only

Treat places where flies rest, e.g. shady sides of buildings and windbreaks, exterior of feed bunks.

Larvae

Treat areas where larvae grow in manure and grass mixtures e.g. drains, hospital and induction area.

Bushflies

Adult flies only – Outside only

Treat places where flies rest, e.g. exterior of feed bunks, pen fences, exterior of buildings, underside of shade cloth, trees and other vegetation.

Blowflies

Treat areas where flies breed or congregate e.g. food waste, carcasses.

What application method to use?

Fly Baits

Fly baits are primarily effective against house flies as they contain sugar and a house fly attractant. Baits will not control a house fly population at a feedlot but can quickly reduce numbers in offices and around feed handling facilities.

  • Scatter baits in areas where flies are or make the bait material into a slurry and paint onto surfaces where flies congregate, as detailed on the product label.
  • Add sugar to residual surface spray products to make an attractive paint-on bait.

Residual surface spray

These products provide both an immediate and long-term effect.

  • Only spray surfaces where adult flies rest.
  • For house flies, spray sunny areas e.g. sides of sheds, feed bunks, and inside buildings.
  • For stable flies, spray the shady sides of fences, feed bunks, buildings and windbreaks.
  • Do not spray on manure.
  • Avoid contaminating feed and water.

Apply with hand-operated sprayers or power operated sprayers at low pressure to avoid insecticide particles drifting away. Spray to the point of run-off but do not allow to puddle.

Periodically rotate insecticides to avoid developing insecticide resistance. Ideally, rotate among different families of chemicals.

Some residual insecticides have restrictions on treating the inside of buildings or being used around animals. Always follow label instructions.

Quick knockdown spray

Also known as space-spraying, or misting, these products provide a quick ‘knock-down’ effect when sprayed directly onto flies.

  • Fills a space with a mist of small droplets that are picked up by flying insects.
  • Has an immediate but only temporary effect on fly populations.
  • Depending on the product, can be used indoors but should not be used where feed is stored or prepared.
  • Can be used outdoors but costs can be high because applications may have to be repeated.
  • Use when fly densities are above tolerable levels.
  • There is no residual activity, so spraying is needed every 5-7 days to be effective.

Typical spray methods include:

Aerosol cans – these are an easy and convenient method of killing small numbers of flies but can be expensive for large areas.

Ultra-low volume misting / Fogging – The fine mists produced by these methods rely on air currents and/or gravity to distribute the insecticide.

Spraying – Concentrations of flies in specific areas can be sprayed directly e.g. on garbage. These treatments may also kill larvae.

Larvicides

Larvicides specifically target the larval stage of insects. Use them to treat areas where fly larvae are growing e.g. manure or accumulations of spilled feed. Because manure is continually accumulating, larvicides have to be applied frequently to ensure good penetration and distribution. Take care when selecting larvicide products as some may also kill the natural enemies of flies (e.g. beetles and mites).

  • Apply directly to areas where fly larvae are growing to prevent the larvae developing into adult flies.
  • Will not deliver instant relief but will provide better control over time.
  • Use cyromazine in preference to other larvicides because it has a lower toxicity and less impact on beneficial insects.
  • Best results when used on areas that are cleaned first.
  • Use in stables, hospital and induction areas of feedlots where straw bedding is not changed regularly.
  • Treat areas that are too wet for effective cleaning.

Apply larvicides with a sprayer or a watering can and apply as emulsions, suspensions or solutions to dry areas. The dosage has to be sufficient to wet the upper 10–15 cm of the substrate. For wet areas, scatter dry granules over the surface as per label directions.

What chemical product to use?

  • Use larvicides and fly baits in preference to adulticides.
  • If an adulticide product is to be used, residual insecticides are preferred over knockdown insecticides.
  • Knockdown insecticides are short lived and fly populations are likely to recover quickly after an application
  • Repeated use of a single product or a single chemical active will result in the development of resistance making it ineffective
  • Rotate chemical groups to slow down the build-up of resistance in the flies
  • All insecticides are poisonous and should be used with caution.
  • Insecticides should only be handled and used according to label instructions.
  • Avoid livestock, feeds and feed preparation areas

Below is a list of the different chemical groups available for fly control

Synthetic pyrethroids/pyrethrins

Organophosphates

Insect growth regulators

Carbamates

Spinosyns

Oxadiazines

Neonicotinoids

A table of chemical actives registered for fly control in feedlots, animal facilities, farm buildings or agricultural buildings are found in chemical groups and actives.

Insecticides can be dangerous if incorrectly applied or managed. Accreditation for chemical use is required for producer quality assurance programmes and conforms to Australia's national training standards. Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for employees. Attending a farm chemical safety training course and/or supporting employees to do the same is strongly recommended.