Growing Beef Newsletter
July 2026, Volume 17, Issue 1
Ticks and flies: time to reapply!
Beth Reynolds, IBC program specialist
Tick headlines are easy to come by in 2026 and for good reason. For Iowa cattlemen, awareness of the Asian Longhorn Tick and Theileria as well as other disease risk is one of the many topics frequenting articles this season. Now that we are into summer, flies are a good reminder that external parasite control is an ongoing effort. That makes now an ideal time to review what strategies were used for prevention, if those strategies actually impact ticks or flies, and the effective window for each.
Product application control methods:
- Applying a spray with pyrethrin or organophosphate based products can be labor intensive but is considered one of the most effective methods to reduce fly and tick populations. However, where the product is applied impacts which pests it is more effective for, given where ticks vs flies are typically found on cattle. For flies, focus on the whole body, especially the face, back and belly. For tick control, focus on application on the face, poll area, tailhead, and scrotal or udder area. The other downside of this method is most products need to be reapplied frequently, and only last for a couple of days.
- Pour-on products with an ivermectin or doramectin based ingredients can reduce horn fly populations but the duration varies. For example, Dectomax is labeled for 7 days of horn fly control while Ivomec has a 28-day label. Neither are labeled for tick control in the U.S. and should not be considered a tick control strategy. For many cattlemen, these products were applied during spring processing and pasture turnout in mid-May to early June. That means reapplication, or utilizing another control method for flies is warranted now. To prevent pest resistance, it is recommended to alternate active ingredient classes when utilizing pour-ons. Similar to spray-on products, how the product is applied matters. Ensure the pour on is applied along the entire back, from between the shoulders to the tailhead as much as possible.
- Like pour-ons, the primary purpose of many injectable products is for internal parasite control, but some (like Dectomax) have fly control applications on the label for a short duration. Again, though it may be speculated, tick control is not included on the label in the U.S. and should not be used as a tick prevention strategy. There are multiple differences between the injectable endectocides products and the efficacy duration. Those with similar ingredients to a pour-on counterpart typically have a similar duration. Alternatively, many are familiar with the extended-release injectable Long Range, which provides a longer 100-150 days of control for internal parasites, but it is not labeled for external parasite control, meaning it is not considered a tick or fly control tool.
- Insecticide impregnated eartags are another option, commonly used for controlling fly populations around the face. These products also deter ticks, but it is worth noting that control around the face, close to the tag will be more effective than control around the tailhead or hindquarter areas. In general, fly control from these products is considered effective for 90-150 days. Effectiveness for ticks is similar, but typically slightly shorter than for flies.
- Finally, there are self-applied products for cattle, typically made accessible in a back rubber, oiler, or duster type situation. These can be effective, but rely on consistent, daily use by the whole herd, and frequent maintenance by the manager. The effectiveness of these products for both flies and ticks is based on how often an animal self-applies the product and would also be influenced by where the product is applied.
When deciding which product to use, review the labels and first narrow down options by limiting selections to those labeled to control the specific fly and tick species of concern. With any and all products, FOLLOW LABEL DIRECTIONS. This year, like most years, the ISU Veterinary Diagnostics Lab has seen cases of improper dilution of an insecticide, leading to adverse effects on livestock when applied as well as insecticide and nitrogen poisoning involving cross-contamination of equipment used around the row crop enterprise and cattle equipment. It is always best to ensure equipment used to haul water and feed have not ever been contaminated with fertilizer, insecticide or similar products.
Other methods:
- Deterring tick populations can involve modifying the habitat. Ticks fall off hosts and molt between life stages before reattaching to a new host. In this timeframe, they need to find an area that protects them from drying out. Burning pastures in spring, clipping grass, and reducing wooded or brush areas that can provide refuge from sunlight are a few methods used to encourage a reduction in the tick population.
- For flies, moist areas - under trees, around water sources, near feeding or other areas cattle urinate and defecate substantial amounts - facilitate growing fly populations by providing sanctuary for eggs and larvae. While there tend to be few feasible options to modify pasture habitat to reduce fly populations, one method is an insect growth regulator (IGR) product in free choice mineral. IGR passes through the animal into manure piles, where it prevents larvae from maturing into adult flies. These are primarily effective for horn flies. Depending on your area, it is worth noting that horn flies can travel up to 10 miles to find a host, so if a neighbor has a fly problem, it is difficult to prevent adult flies from finding your herd.
- Garlic in the mineral is a natural method to deter insects that has gained popularity. Rather than disrupting the reproductive cycle of flies, consuming the garlic powder theoretically results in flies being less likely to land on and bite livestock. However, long term effectiveness to reduce fly populations on the animal to below the economic threshold is variable. One of the more promising studies out of Canada reported nearly a 50% drop in fly counts per cow in the garlic consuming group. When repeated a second year, it did not observe a similar reduction. An interesting note within that study was a bump in free-choice intake when garlic was included. That serves as a good reminder to track intake in order to meet herd goals while keeping a handle on costs. Garlic inclusion’s effectiveness for deterring ticks is also inconsistent and hard to measure, but no known negative effects have been reported.
No fly control or tick control measure should be considered a “one and done” strategy. All measures have their place, depending on the goals and environment of each operation. Work closely with your veterinarian to develop a well-rounded strategy to control flies, ticks, and other parasites to keep your herd healthy and performing.
This monthly newsletter is free and provides timely information on topics that matter most to Iowa beef producers. You’re welcome to use information and articles from the newsletter - simply credit Iowa Beef Center.
