Fly Control: Prepping Now Pays Back

Fly Control: Prepping Now Pays Back

Higher seasonal temps and more variable weather can accelerate parasitic and nuisance fly pressure. A dairy farm's Integrated pest management (IPM) program ought to be able to anticipate fly challenges that will impact milk production.

Losses to flies on dairies are difficult to quantify, but they are significant and may be underestimated as recognized in the scientific literature going back decades. Today, "activity and rumination monitoring systems" and other precision dairy technologies are helping to measure how fly infestations negatively impact cow comfort and feeding behavior.

Fly season

Coming into fly season means anticipating weak points in the dairy's IPM, says Dr. Ulises Sanchez  at New Mexico State University. He advises that every IPM plan should include key elements:

• Fly ID -- confirming "pests of concern," particularly stable flies (Stomoxys calcitrans), horn flies (Haematobia irritans), face flies (Musca autumnalis), house flies (Musca domestica)
• Cultural control -- limiting fly breeding and feeding by reducing feed residue, silage effluent, access to manure (including intermittent slurry and lagoon "beaches")
• Mechanical control -- fly traps, lighting, etc.
• Biological control -- parasitic wasps, etc.
• Chemical control -- pesticides (surface applications, topical treatments, ear tags, injectables), feed-through insect growth regulators (IGRs)

Stable fly (Stomoxys calcitrans), courtesy of University of Florida 

No "silver bullet"

"But no single element or tool in the IPM is a 'silver bullet'," Sanchez cautions. "Each dairy operation is unique and a huge number of variables can influence a potential infestation.

"Those same variables -- from food availability to weather -- also limit our ability to measure outcomes from individual elements of the IPM."

Despite these limitations, Sanchez points out, to be effective the IPM program also must be dynamic. It must be able to adjust quickly to changing farm conditions and stages of infestation. For example, stable flies can develop from egg to adult within two weeks, other species in as little as a week, resulting in very rapid population growth.

Control

When it comes to control, Sanchez points out that, unlike organophosphate and pyrethroid insecticides, IGR compounds have no documented cases of resistance. This is because IGR molecules like diflubenzuron interfere with chitin formation, causing early molting of larvae resulting in exoskeleton malformations, whereas methoprene is an insect growth hormone analogue that prevents the pupa from molting to an adult.

Moreover, Sanchez adds, IGR feed-through products might be purchased to control a certain fly species but will also help reduce populations of other fly species that use manure for immature development.

Today, non-farming neighbors are more sensitive to fly populations, including greater numbers of the nuisance commensal house fly. So, shoo flies!

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