External parasites, especially horn flies, can have a serious economic impact on beef herds in Arkansas and all across the South. These pests usually become a concern for producers in mid-summer through late fall. It is generally agreed that economic losses occur when fly numbers exceed 150 flies per animal. Therefore, it is necessary to control horn flies in cattle to maximize economic returns and enhance animal welfare.

A fly control demonstration was performed with the cow herd at the University of Arkansas at Monticello beginning in August of 2014. Here we evaluated two aggressively marketed fly control products which included XP-820 fly tags manufactured by Y-Tex corporation and Aim-L Vetcaps marketed by Agrilabs. The XP-820 fly tag is a slowrelease product containing abamectin, which had not been previously used in the United States. This tag is labeled to control horn flies, including strains resistant to synthetic pyrethroids, and several tick species. The Aim-L Vetcaps are softgel capsules that contain10 ml of lambda-cyhalothrin with piperonyl butoxide. They provide horn fly and lice control for cattle over 600 lbs. The Vetcaps are applied with a Vetgun, a remote delivery system that is designed to save time and reduce handling stress by allowing the product to be applied to cattle in the pasture.

The demonstration began on August 7, 2014. This herd consists of approximately 90 Brahman-influenced females and was divided into three equal groups with fly counts being recorded prior to treatment. One group of 30 cows served as our control group that was untreated. The second group of cows were brought to the corral and had one XP-820 fly tag applied. The third group was treated in the pasture with the Aim-L Vetcaps using the Vetgun. The time required for treatment and the cost per head were recorded for both treatment groups. Fly counts were performed weekly to evaluate the efficacy of the two products.

On August 7, 2014, prior to any fly control treatment, fly counts averaged greater than 200 horn flies per animal for all three treatment groups. For this demonstration, all fly totals exceeding 200 per animal are listed as 200 plus. The time required to gather the 30 head of cattle from the pasture, move them to the corral, apply the XP-820 tags and return them to the pasture was 55 minutes. Keep in mind that the university has above average working facilities and workers readily available for assistance. The time required to administer the Vetcaps to the second treatment group was 24 minutes. Some practice is required to develop a high degree of accuracy with the Vetgun. Additionally, a rainfall event within 24 hours of Vetcap application can negatively affect absorption and duration of the product. Approximately three hours post treatment, two-tenths of an inch of rain was recorded on the university farm.

One week post application, fly numbers had dropped significantly for the XP-820 group to approximately 20 flies per head. The Vetcaps group had also declined to approximately 120 flies per animal. Two weeks post application, the XP-820 group was even lower at approximately 10 flies per animal; however, the Vetcaps group had returned to around 200 per animal. On August 21, 2014, fly numbers were back to pretreatment levels for the Vetcaps group, and the decision was made to readminister the Vetcaps since a rainfall event occurred only three hours after the first treatment. One week after the second application with Vetcaps, fly numbers in this group were down to approximately 20 per animal while the fly tag group remained at approximately 10 flies per head. On September 4, 2014, the Vetcaps group had risen slightly to approximately 50 per animal, and the fly tag group had increased to 20 flies per animal. By September 11, 2014, the Vetcaps group fly counts had returned to pretreatment levels of almost 200 flies per animal, while the fly tag group was still less than 50.

In summary, horn fly control is essential for maximum productivity and profitability in beef cattle operations. In this demonstration, the Vetcaps fly control product did provide effective horn fly control but only for approximately two weeks post treatment. While it does require less time for application and possibly less handling stress, the cost of the Vetcaps and Vetgun, along with the need for multiple applications per fly season, leads us to the conclusion that the XP-820 fly tag is the most beneficial and economical of these two products. The XP-820 tags suppressed horn fly numbers below 50 flies per animal for seven weeks and below the threshold of 150 flies per animal for a total of eight weeks. Talk to your herd health veterinarian and start planning now for the horn fly control strategy that best fits your operation.