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BUZZ OFF! By Michael Cox for American Cattlemen Magazine


espite some challenging cold weather throughout the States this Spring, the summer heat has inevitably arrived, and with it, the nuisance issue of controlling flies on cattle. Summer fly control is a crucial component of a profitable rancher’s management plan, as fly irritation to cattle can greatly reduce daily live-weight gain and lead to animal health issues such as pinkeye. Flies disrupt grazing, particularly in growing calves, leading to lighter weights come weaning time. The horn fly is typically the worst summer offender, with face flies and stable flies also contributing to the pest pressure. Horn flies have a rapid lifecycle of 10-11 days allowing an explosion in fly populations to occur in a matter of a few weeks. The threshold level for cost-effective fly control is 100 flies per calf and thankfully, there are many options available for effective fly control. Chemical

The majority of fly control options are chemical based, although there are a small number of natural preventative measures that can be taken. Insect Growth Regulators (IGR) are a low-labor fly control option. IGRs can be fed to cattle through feed supplement or minerals. The compounds have no negative effects on animal performance, as they specifically target the larvae development of the flies. Care must be taken to ensure that sufficient intakes are being regularly

achieved by the cattle, particularly if the IGR is delivered through free-access minerals. Most IGR products recommend that the feeding program begins approximately one month prior to fly emergence. Dust bags and back rubbers/ curtains are another labor friendly option that rely on physical contact with the animal to deposit insecticide onto the face and back area of the cattle. The applicators must be set up in a high-traffic area where cattle will regularly pass under them

to access water or feed. Animals should be grouped according to size/ height to allow equal application to every animal. Apart from protecting the applicators from rain and replenishing the insecticide, there is almost no maintenance or workload involved in this control method. Summer worm-control treatments can also be a useful method of ‘doubling-up’ as a fly-control treatment. Ivermectin pour-on based products used primarily for roundworms, lungworms etc. will also offer a short time period of horn fly and lice protection. The fly control benefit of pour-on products should be viewed as an added bonus to worm control, as pour-ons are usually insufficient for use as a full fly control option on its own. Direct insecticide spray offers cost-effective prevention and can be best used to rapidly reduce fly-load on badly affected cattle. Some fly sprays can be diluted with oil or diesel to help the insecticide stick to the hair for longer. Resistance issues can build up over the season if the same class of insecti* Continued on page 22



June 2018

American Cattlemen June 2018  
American Cattlemen June 2018