Plan Ahead for Fly Control

As warmer weather draws near, so do fly populations. Be ready with proper sanitation and control measures.

Beef cattle producers across the country worry about flies because they are blood suckers. And not only do they suck blood, but they spread diseases such as pinkeye – and can blow a hole through the heart of an otherwise profitable beef cattle operation.

Arguably the biggest culprit around beef cattle circles is the horn fly. It was so named years ago because it rested on the horns of cattle – back in the days when most cattle had horns. Today though, horn flies tend to rest on the withers, back, and sides of cattle. They do most of their blood sucking on an animal’s under-side, where most of their biting occurs, explains Dee Whittier, DVM, Extension Veterinarian, Virginia-Maryland Re-gional College of Veterinary Medicine.

Losses associated with horn-fly infestations have been studied extensively. The crucial level of flies at which losses begin to occur is 200-250 per animal.

“If either young animals or cows have this many flies or more, treatment will result in increased weight gains,” Whittier reports.

Studies done at Texas A&M University have documented average increases in weaned calf weights of 20-27 pounds when effective control of horn flies is implemented.

The second major type of fly that affects pasture cattle is the face fly. This fly is larger and more robust than the horn fly, and spends only periodic feeding times on cattle during the day. As the name implies, these flies prefer to be on the face and consume the secretion formed around the eyes and nostrils.

“Face flies are particularly important because they transmit the pinkeye organism from one animal to another. They damage the cornea of the eye during feeding and, thus, allow a port of entry for the pinkeye-causing organism,” Whittier shares.

Effective programs available for fly control

A number of methods and products are available for the control of cattle flies. More emphasis has been placed on horn fly control, perhaps because their study is less complex and they are generally easier to control.

The topical products that are currently available and approved for control fit into four major categories: organophosphates (OP’s), pyrethroids, organochlorines, and endectocides. Pyrethroids have, to date, given the best face fly control because of their ability to cause rapid knock down.

When making decisions about fly control, it is important to realize there are many effective programs. Producers should develop a program for their operation which is cost effective and most convenient.

Whittier suggests these factors to consider when developing a herd fly-control program:

• Young cattle should receive more attention than older cattle; they are growing, so decreases in gain directly affect income.
• Young cattle are much more susceptible to pinkeye.
• Depending on the region, full-season control from fly tags, especially for face flies, is generally not possible.
•  Newer pyrethroids and OP’s have been slower to develop resistant flies.
• Combination pyrethroid and OP products are quite good against resistant flies in theory.
• No resistance to endectocides has been reported.
• The use of two fly tags (one in each ear) extends control by 10-14 days in most areas.
• Dustbags, oilers, face mops, and other “self medicators” can be very effective because they provide for long-term high concentrations of insecticides on cattle.
• Locations for “self-medicators” must be carefully chosen so that cattle will get frequent contact.

Whittier points out the horn and face flies found on pasture cattle differ in species from the house and biting stable flies – or “filth flies” as they’re also known – found at feedlots. Regular cleaning, monitoring, and maintenance of typical fly breeding habitats will help reduce fly populations in these areas. In general, a clean and tidy operation will have less fly problems than a messy one.

Beef cattle specialists with Alberta Agriculture and Rural Development have developed a checklist of sanitation and control procedures that, when followed, can dramatically reduce fly populations around the farm, ranch, and feedlot.

Potential fly breeding areas: Manure

• Moist piles of manure and bedding.
• Moist areas in pens due to surface water.
• Areas around and under waterers.
• Under pen fences and in pen corners.
• Alleyways and cattle processing areas.

Potential fly breeding areas: Feed

• Wet spilled feed around and under bunkers.
• Old feed in bunkers.
• Silage effluent or spilled silage – front and sides of horizontal silage silos and piles or the base of tower silos.
• Around and beneath stored hay bales – where bales contact the soil.
• Spilled feed around feed mixing areas and under augers.

Recommended Control Methods:

• Stock pens at high density to compact and trample manure.
• Remove spilled feed and silage weekly.
• Enclose or fill in under feed bunkers.
• Construct concrete aprons around feed bunkers and waterers.
• Clean sick pens frequently.
• Scrape and grade pens frequently, filling low areas and contouring for runoff.
• Minimize seepage from silage.
• Raise bottom railings high enough to clean underneath.
• Divert surface water by grading and providing drainage around pens and facilities
• Keep vegetation mowed short around the operation.