As we move into the warmer time of the year these pests will be coming out in full force. They will be coming out of their dormant stage to feast on your cattle negatively affecting your herd’s production. But what is a rancher to do?!
Though you will never fully get rid of them there is a way to get them under control. In order to be the most effective, it will require a multi-prong approach. It will require all of them because just using one will not get the results that you are looking for.
Types of flies to control
When it comes to beef cattle there are typically 3 types of flies that you will have to deal with. These types are Horn flies, Face flies, and Stable flies.
Horn flies
Courtesy of University of Florida Entomology
- These are typically smaller in size than the other types that you will deal usually 3/16″ in length. They are blood feeders that require more than 30 meals per day.
- They are usually found on the backs, sides, and poll areas of cattle. During the warm summer afternoons they will also be found on the belly regions of cattle.
- Though they are small in size the impact that they have on the cattle industry is very large. Economic losses from them are estimated at more than $1 billion annually.
- Since they feast on blood they have also can cause weight loss in cattle. Studies in the U.S. and Canada have shown that horn flies can negatively impact weaning weights by between 4-15%.
- Typically these flies will not travel very far so controlling them will be a little easier
Face Flies
Courtesy of University of Nebraska-Lincoln Entomology
- When these are in the adult stage they can look very similar to house flies though they are slightly larger and darker in color. Another thing that separates these from the other types is that as the name implies they will be found mostly on the face area of a cow.
- It is a non-biting fly that feeds on animal secretions, nectar, and dung liquids. The adult female will cluster around the cow’s eyes, mouth, and muzzle. As you can guess this can be quite an irritation to your cattle.
- They can be found throughout the summer months but their population numbers usually peak in late July and August. Also, they will be more numerous along waterways and areas with abundant rainfall.
- These flies have been shown to travel farther distances than most, usually 1-2 miles. So if your neighbors are not taking steps to control these it will be near impossible for you to do so.
- While feeding they can cause damage to the eye tissue which will increase the chance of some type of infection to the eye. One of the most common that will occur is pinkeye which is a contagious inflammation of the cornea. I talk more about the steps you can take in preventing and treating pinkeye in a previous article “4 Common Summertime Diseases”.
Stable Flies
Courtesy of University of Florida Entomology
- Like the horn fly this is a blood feeder that is a serious problem on feedlots, dairies, as well as pasture cattle. It will mainly be found on the front legs of the animal.
- The bites from these insects are painful and will cause cattle to stomp their feet or bunch together in the corner of a pasture to get away from them. They will also make cattle stand in water to avoid being bitten by these little pests.
- Typically these flies will develop around feed bunks, under fences, and around stacks of hay. Also, sites, where you fed hay during the winter with hay rings, can also be a source of larvae development if the right amount of moisture is present.
- Also, like the horn fly an overabundance of stable flies has been shown to cause weight loss and less production in cattle. Studies that have been conducted show a recorded reduction in ADG, or average daily gain, averaging around 1/2 lb. per head.
Methods of fly control
As I mentioned earlier it is impossible that you will completely get rid of flies but with proper management, you can get them to a level that will not affect your production. There are 5 steps that you can take to lessen the impact flies will have on your cattle.
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Feed an insect growth regulator
- Usually, you can get this with certain types of mineral supplements like Altosid or Rabon
- Altosid is labeled just for Horn flies and Rabon is labeled for Horn, Face, and Stable flies
- In order to be most effective, you will need to start putting this out 30 days before flies typically start to emerge and continue feeding it until 30 days after a killing frost.
- What this product does is stop the growth cycle in the larvae stage.
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Fly Tags
- Some of the fly tags coming out now have a higher concentration of insecticide in them and are very helpful in controlling fly populations
- Since there are two types pyrethroid and organophosphate. What you to do is to use the pyrethroid tags for 2 years then use the organophosphate for 1 year to reduce resistance
- Depending on which type you use it may require 2 tags per adult and 1 tag per calf for optimum control
- The key to using this is that you will want to wait till you have 200 flies per cow before you use them. Using them too early can reduce their effectiveness.
- Remove the tags 3-5 months of use in order to prevent the possibility of resistance issues
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Pour-Ons
- You will want to apply this at the same time you put the tags on your cattle
- When you are doing this during the spring you can use a product that will also kill internal parasites. Since those products have been shown to work against horn flies. If it is later in the year only use a product that is labeled for flies and/or lice. This will prevent the likelihood of internal parasite resistance
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Dustbags/cattle rubs
- If it is placed at a site where all cattle will end up using it this can provide a very economical way of face and horn fly control
- Keeping them charged with insecticide and putting them in the proper places is the key to using this
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Sprays
- Spraying your cattle throughout the year can be an effective way of controlling the fly populations on your ranch.
- This can be very time consuming though if your cattle are grazing a very extensive area
There are many different sources you can search for in order to find a way to control flies. Your local county extension office is one place to start. The Texas AgriLife Extension Service also has a publication titled “Managing External Parasites of Texas Cattle”.