Altosid® IGR

Costing the North American cattle industry over $1 billion annually, horn flies are a major concern for pastured beef cattle. Despite the fact that these pests cause weight loss and are vectors for beef heifer mastitis, many ranchers do not take action when it comes to controlling them.

Conventional fly control methods such as ear tags and pour-ons reduce populations through direct toxicity. Horn flies in many areas have developed resistance to these labor-intensive methods as a result of overuse. Alternative methods include feed throughs like Altosid® IGR. Requiring little to no labor, this option controls flies by interrupting their life cycle during the larval stage. The active ingredient in Altosid® IGR has not had any cases of resistance since its introduction to the market place in 1975. Further, because Altosid® IGR is formulated for beef cattle on pasture, it specifically targets horn flies without causing damage to beneficial parasites and other fly species. A recent study confirmed that stocker cattle treated with Altosid® IGR, a feed-through horn fly control solution, experienced a 15.8% increase in average daily gain compared to cattle who went untreated.

Understanding the Problem

Horn flies are the most common fly species on pasture. And while these bloodsucking parasites may be small, they make for big problems. Each fly can take up to 40 blood meals a day, causing stress in cattle. Consequently, cattle expend extra energy trying to dislodge flies and normal feeding patterns are disrupted. Along with blood loss, this leads to significant reductions in weight gains.

The best way to identify a horn-fly infestation is to look for groups of small flies congregating on specific parts of cattle. Observations made between 9AM and 1PM are most accurate, as this is when horn flies are located in visible areas like the back and shoulders. It is important to note that horn flies stay on the cattle day and night – the only time they leave is to lay their eggs in fresh cow manure.

How Feed-Through Products Work

Conventional pesticides attack the nervous systems of flies. A feed through, such as Altosid® IGR, works by interrupting the fly’s life cycle rather than through direct toxicity.

Altosid® IGR is ingested with the cattle’s mineral or feed. As they graze, cattle disperse the IGR via their manure, where female flies lay their eggs. The eggs hatch into larvae, and after three to five days they molt into pupae. At this point, however, the active ingredient in Altosid® IGR disrupts the development of the fly by naturally mimicking the biochemicals that are responsible for insect development. The fly life cycle is effectively ended here.

For best results, Altosid® IGR should be added to your feed supplement 30 days before fly emergence (typically when average daily temperatures reach 65 degrees) and continued throughout the season until 30 days after the first frost.