Insecticides have been placed into 29 different groups based on how they work—their “mode of action”—against insects.
Of these 29 groups, only seven contain products that are registered for fly control, and among these seven groups, only five include products to control adult flies.
Continual use of products from a single mode of action against a pest species can lead to reduced control by—and eventually resistance to—all products in the group.
To minimize control failures due to insecticide resistance, do not repeatedly apply insecticides from the same group, even when using different application methods (baits, residual sprays, knockdown sprays, etc.).
Rotate among mode-of-action groups during the fly season. For example, for house-fly control, alternate between an organophosphate like tetrachlorvinphos (Group 1) and a pyrethroid like cyfluthrin (Group 3) for residual sprays, and use a fly bait containing imidacloprid (Group 4).
Sanitation and moisture control are key steps in reducing stable- and house-fly numbers around barns and confinement areas. Breeding sites include wet manure, straw, decaying feed and mixtures of these materials. Keep areas around cattle pens, feed bunks and silos clean and well drained.
Insecticide treatments will work better when used in conjunction with an ongoing sanitation program to eliminate breeding sites. Immediate spreading of manure will reduce fly development, or manure piles can be covered with black plastic to kill larvae.
Insecticides may be applied as residual surface sprays, non-residual space sprays, baits or feed additives. Always read and follow label instructions before applying insecticides for fly control.
Surface Sprays. Treat walls, ceilings, posts and other fly-resting sites. Accumulations of fly specks (waste spots) on surfaces will show where residual sprays should be applied. Spray these areas thoroughly to get good coverage but not to the point of runoff, and be sure not to contaminate food and water, and do not treat animals directly.
Residual fly sprays typically provide control for one to seven weeks depending on fly infestation, weather and surfaces treated.
Rotation of pyrethroid and organophosphate insecticides can reduce the potential for development of resistance.
Fogs and Space Sprays. These provide rapid, but short-term, control of flies present during treatment. Repeat as allowed by the product’s label.
Not all fogs and space sprays can be applied when animals are present. Read the label of the product carefully to make sure you apply it correctly. Do not apply space sprays directly to livestock.
It is best to alternate applications of pyrethroids (deltamethrin, permethrin and pyrethrins) with organophosphates (dichlorvos and tetrachlorvinphos) to reduce the potential for insecticide resistance. See the label for use rates and application directions.
Fly Traps and Baits. Large numbers of flies can be caught in baited fly traps, but the traps may not significantly reduce total fly numbers.
Electrocuting light traps may reduce house- and stable-fly numbers in closed buildings.
Fly baits can be scattered outdoors where house flies congregate to provide some temporary reduction in numbers. Place baits in areas outside of barns, feedlot pens and other places where flies frequent. Never use baits where cattle or other animals can eat them.
Fly traps and baits do nothing to control fly breeding sites. That’s why sanitation and other insecticidal treatments, e.g., residual and space sprays, are so important.
Feed and Mineral Additives. Premix larvicides can be used for fly control, but be sure to read label instructions carefully to ensure all animals are receiving adequate levels to kill fly maggots.
Fly Parasites. Release of fly parasites that are available from several commercial firms can be used to effectively supplement fly control around confined livestock operations. These small wasp parasites attack both house and stable flies.
For more information about insecticide modes of action and rotation, visit: http://www.irac-online.org/.