Fly control in cattle

Farm Forum

It appears that for most of South Dakota we’ll be blessed with ample grass growth for the grazing season. It’s always been satisfying to me when the last group of cattle is turned out to pasture and for a time at least, daily feeding chores have ended.

Of course there are two sides to every coin, and one of the problems we deal with during the summer is fly control. We all know that increased numbers of horn and face flies cause performance losses and can contribute to the incidence of pink eye and even mastitis. The challenge is coming up with control strategies that are effective but also relatively easy to implement. Control practices that are easy and simple sometimes don’t work well; strategies that are very effective usually require additional labor and management.

We tend to put a lot of focus on deciding what techniques and products to use. In my opinion, too often we overlook factors such as the timing of treatments. It’s very tempting to treat cattle at turnout for external parasites because they are already grouped and confined. Unfortunately in a lot of cases treating at that time doesn’t match with the peak fly pressure. That can result in less than desirable control late in the season that requires another treatment.

The good news is we do have a number of tools available. Some of those options are highlighted below with a few comments. One of the keys to success regardless of the control method used is that effective external parasite control should involve multiple strategies rather than relying on one method every year. Rotating different insecticides (pyrethroid and organophosphate) and/or different control measures will help to make sure that our fly control efforts remain successful.

• Fly Tags: These can be placed in the cow and/or the calf. Rotating chemical families and proper timing are critical factors in the success or failure of fly control strategies involving fly tags.

• Feed-through Products: The theory behind these is that the product is passed through the animal, into the manure patty, where it then affects the larvae, breaking the cycle before they have a chance to hatch and feed on the cattle. Achieving consistent intake is a key factor in how well these products work, but there is no additional labor required other than providing the supplement. Keep in mind that flies could still come in from adjoining pastures. Also, methoprene, (Altosid®) is only labeled for horn flies. If face fly pressure becomes an issue, additional control measures would need to be implemented.

• Dusters and Oilers: The biggest advantage to these strategies is that treatment timing can be matched to fly pressure. Making sure that the cattle use these treatment stations and that the insecticide supply doesn’t run out are the key success factors.

• Individual Animal Treatment: This includes pour-ons and sprays as well as the new application methods that work like paintball guns. The big advantages are that treatments can be made when the fly numbers dictate. The challenge will be getting all the cattle gathered and treated, depending on the exact product being used.

• Pasture Rotation: The impact of pasture rotation and management on external parasites is often overlooked. Placing greater distance between the previous and current pastures when feasible can help break the fly life cycle.