Drovers CattleNetwork news source   |   Updated: February 2, 2012

It’s that time of year when all livestock producers should be implementing fly management strategies. There are several management decisions that can be made that will greatly decrease fly populations in and around livestock facilities. Fly control should be viewed as a good neighbor policy and having a positive economic impact on your livestock operation.

There are four primary types of flies that producers need to be aware of and that likely have the greatest impact on your operation. Face, horn, stable, and house flies are the most common flies we have around the farmstead. It is extremely important to correctly identify the fly or flies you wish to control. Following is a brief description of each fly control methods.

Stable Fly
Stable flies require a combination of organic matter, animal waste, and moisture to reproduce. They can reproduce in about 24 days. They are blood feeders that can have an economic impact with no more than 20-25/animal unit (AU). This fly can cause animal stress that will reduce animal weight up to 20-25 lb/AU. This fly will over-winter in undisturbed and protected areas around buildings and feed bunks. An adult will lay approximately 800 eggs in groups of 25-30 after a blood meal. Their favorite location is on the lower legs.

Control
The best management practice to control this fly is sanitation. In other words, if you can break the cycle of egg production, you can make rapid progress in controlling fly numbers. Also, starting early in the growing season is always helpful. The best way to do this is by removing spilled feed, cleaning barns every 7-10 days, and minimizing water spillage. Another method is use of dust bags (located in strategic areas), baits, laravacides, and sticky tapes. My recommendation is to either use a combination pyrethoid/organophosphate tag or if using only one of those insecticides, rotate the type of tag used each year. Another newer method is using parasitic wasps. This small insect will attack fly larvae and prevent larvae from hatching. This is an effective tool provided you use the right parastoid and you do not wait until the stable fly population is out of control. There are several companies that sell this product and you can contact your local Extension office for this information.



Horn Fly
The horn fly is one of the most costly of all flies to the livestock industry. This fly is typically located on the shoulder area of cattle and after reaching thresholds of 100-200/AU will decrease animal performance. Fly numbers of 500/animal can remove up to ½ lb of blood per day. In addition, we know that animal performance in feedlots can be reduced by 10-15 lb. of gain per week if fly numbers are left uncontrolled.

Control
Controlling the horn fly starts in the pasture or through the manure that is deposited by grazing or feedlot animals. Rabon or Alstoid are effective products that can be added to your mineral program to reduce horn fly numbers. In addition, fly tags, backrubs, and pour-ons can be effective in reducing these fly numbers. In each case, one has to look at cost and management style to determine which of these tools you should utilize. Start early in southern Michigan (around April 20th) and later as you go North (around May 10th).

House Flies
House flies are more of a nuisance than an economic impact on livestock. Like stable flies, house flies require manure, organic matter, and moisture to reproduce. Adults live 3-4 weeks and can produce up to 1000 eggs each. Cleaning barns every 7-10 days and sanitation can go a long way in controlling or reducing house fly numbers. The biggest concern with this fly is the spreading of disease and the impact on your neighbors. House flies are generally seen more around buildings than in pastures and do not have sucking mouth parts like the stable or horn fly.

Control
Control measures for this fly are very similar to the stable fly. Most of these flies depend on organic matter to reproduce and breaking the cycle is accomplished by using sanitation methods and keeping barns as clean as possible. Minimizing water and feed spillage can be very helpful in controlling this insect. Note, when controlling flys, that means cleaning corners and areas that you might not reach with skid loaders or power equipment. Once again, a parasitic wasp is an option along with larvacides, sticky tapes, and fly baits. The important method of control goes back to starting early and using the right tools at the right time.

Face Fly
The face fly’s greatest impact is the spreading of disease. It can reproduce in pastures. Face flies are especially responsible for the spreading of pinkeye. For those of you that have had experiences with this disease, know the economic impact and time commitment it takes to treat affected animals. The life cycle of this fly is between 14-21 days. This fly can also over-winter in manure.

Controls
There are several things that you can do to control this fly. Insecticide ear tags, strategically placed dust bags, backrubbers, pour-ons, and some animal sprays can be effective management tools to help reduce fly numbers. Once again, starting early will lead to successful reduction of this particular fly.

Other flies occasionally impact grazing livestock. In most cases, there is no clear method of control that will reduce the impact these flies have on livestock. Many of these flies, such as heel or horsefly reproduce in areas of the farm that have standing water. Controlling these types is nearly impossible. In many cases the only relief livestock receive is through utilization of shelters. Shelters may include walk through devices or umbrellas. Once again, the producer that starts early will most likely succeed but if you wait until fly numbers are out of control you may require a different approach to fly management.

Always remember to:

• Strictly follow label directions.

• Remove old tags at the end of the season.

• Alternate fly tag insecticides each year.

• Use plastic gloves when handling fly tags or insecticides.

• Keep records on what insecticide you use from year to year.

• Contact your AoE educator if you need assistance with proper use and timing of fly control for your area.

Source: Maury Kaercher, Michigan State University Extension Livestock Educator, SW MI

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