Protect Your Calves During Fly Season

( Maureen Hanson )

With fly season at its peak, calves need extra protection to stay healthy and stress-free.

Stable flies are particularly damaging to calves, because their painful bites on the lower legs are stressful and damaging to calves’ tender skin. Sarah Morrison, researcher at the W.H. Miner Institute,  Chazy, NY, said the damage from stable flies can be severe enough to cause noticeable hair loss and scab formation. “Stable fly populations will increase throughout the summer, and have the greatest numbers by the end of August and early September,” noted Morrison.

Biting flies like stable flies also have been identified as a vector that can spread vesicular stomatitis, which is a growing concern in the southwestern U.S. Common houseflies are more of an annoyance but also can spread diseases, and have been recorded in populations as much as 8-fold greater than stable flies.

“Unfortunately, calf housing is an awesome breeding ground for fly populations on the farm,” said Morrison. “Fly maggots grow and develop in accumulations of manure; spilled grain and milk; other spoilage piles; and straw bedding.” 

She noted an Integrated Pest Management (IPM) plan can be helpful in minimizing fly populations and protecting calves from their damage. IPM focuses on (1) sanitation; (2) biological control; and (3) chemical control. For IPM in calf environments, she advised:

Sanitation – Clean pens weekly and remove excess manure regularly. Mow areas around calf hutches, and elevate hutches to encourage airflow and keep bedding dry. Consider sand, gravel or sawdust as bedding materials instead of straw in warm-weather months.

Biological control – Releasing natural predators in the spring can help keep fly populations from blooming. These natural enemies include black soldier flies, rat-tailed maggots, beetles, mites and wasps. 

Chemical control – Chemical sprays should be rotated to prevent insect resistance. Larvicides can be used in heavy breeding areas such as manure storage, but should be used with caution because they also destroy beneficial insect populations. Oral, feed-through larvacides are especially helpful in managing fly populations in calf environments. Baits and traps also are useful in lowering adult fly populations throughout the farm.

“A whole-farm approach should be taken to maximize fly control, and also will positively impact the calf-rearing area,” said Morrison. “Plus it also creates a more pleasant environment for the people caring for the animals.”

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