Livestock fly control considerations

Farm Forum

Even though spring warm-up has been delayed, the mild winter suggests we could have overwintered a lot of insect eggs, possibly leading to an onslaught of summer bugs such as flies. We should prepare for a long and possibly heavy load of face and horn flies on pasture cattle this summer. Here are some tips and suggestions for fly control.

There are various options available, but it is important to evaluate these and determine which is going to give you the best control in your situation. In some situations a combination of applications may provide the best control.

One option is fly tags. They can be placed in the cow and/or calf and will provide some protection to both. When using fly tags it is critical that you change the class of chemical that you use each year because flies can develop resistance to one type of chemical, and therefore a different chemical is needed to control that pest the next year. The two main classes of chemicals used in insecticidal fly tags are pyrethroids and organophosphates, both of which can contribute to resistance in fly populations. There is a new class of chemical that claims no resistance. This contains the active ingredient Abamectin. When tagging the animals, always follow label directions to determine the age of animals that can be tagged as well as how many tags to put in each animal. This will vary by tag and active ingredient, so follow the label for best fly control and to decrease the incidence of resistance. Branding time may be a convenient time to put fly tags in, but it may not be the best time because it is too early in the fly season and effectiveness of the tags will be diminished by late summer when it is needed most. Additionally, calves may be too young at branding to apply tags to them.

Another option is dust bags. There are two main products that can be used in dust bags. These are Coumaphos (Co-Ral) and Stirofos (Rabon). The key with dust bags is to ensure that the bag is tightly woven and does not have any holes. The bags should be placed where cattle will use them regularly. This could be near salt and mineral blocks, a water source, or shelter/shade of any kind. It is important to keep the bags as dry as possible to keep the product from being affected by moisture, resulting in caking in the bag.

A third fly control method is to use oilers. There are three main products to use in oilers. These include Coumaphos (Co-Ral), Permethrin, or Malathion. Read the label directions to determine how these products should be mixed. Like dust bags, oilers should be placed where cattle will use them regularly. When using an oiler or backrubber, make sure that the insecticide is not dripping and contaminating water supplies.

The fourth method is insecticide inclusion in the mineral. Ranchers can purchase mineral with fly control insecticide included. One of the insecticides is Altosid. Livestock ingest the insecticide and then it is excreted in the manure. When the larvae feed on the manure the Altosid stops the development of the pupal stage, thus breaking the fly’s life cycle.

Other means of chemical control include pour-ons and injectables. These have varying lengths of efficacy on different pests, and can be a part of your overall pest control program.

There are also some natural pest control methods that can be used, aside from or in addition to chemical control. One such option that is more effective for lice control is the use of diatamatious earth. This is a natural compound that can be used in a dust bag, and will act to puncture the shell of the pest. In other words, the flies and lice die because of physical damage, not chemical toxins. Dung beetles are also helpful in fly control, as they act to cool the manure off more quickly, which eliminates the optimal environment for the fly larvae to survive, however they can be negatively impacted by the use of diatamatious earth.

Finally, well-timed pasture rotations can also contribute to fly control because the livestock are moved away from their manure before fly larvae emerge, so the life cycle is broken.

Fly control is important; it is well documented that both blood sucking and altered livestock behavior due to irritation contribute to poorer livestock performance. Fly control practices need to be strategic so that they reduce the fly population to the degree that performance is not harmed, but at a reasonable cost. Timing of application is also critical, and sequential use of combinations of these practices will probably be needed if this is going to be a longer than normal fly season.

For more information, contact Ken Olson at the West River Ag Center at (605) 394-2236 or contact any SDSU Extension Cow/Calf Field Specialist or Beef Extension Specialist.