Once a year the ladies (and their babies) get their earrings. The pretty blue circles make a grand statement against a canvas of black cattle and green pasture. I really don’t think the cattle care about how they look (I mean they get themselves muddy pretty quickly) but I’m pretty sure they care about that annoying fly on their back….so what do those pretty pastel blue circles do?
They tell the fly….Shoo fly don’t bother ME!
Types of flies
Horn flies are small and normally found on the sides, backs, and bellies of cattle. Horn flies live on approximately 30 blood meals per day. Fly populations can easily reach over 200 flies per cow. That’s 6000 bites per day. Female horn flies lay her eggs in manure and they hatch within one week. They complete an entire life cycle in just 10-20 days depending on the weather.
Face flies look similar to house flies but are slightly bigger and darker. They are non-biting and feed on animal secretions, nectar, dung liquids, blood, and and other secretions around wounds. Female face flies cluster near cattle’s eyes, nose, muzzle, and mouth causing annoyance. Face flies are present all summer but the population peaks during July and August and are more numerous along waterways, areas with significant rainfall, and areas of shaded vegetation.
Stable flies are blood feeders who bite the legs of cattle. While stable fly populations typically stay much lower than horn and face fly populations their bites are very painful and cause the cattle to stomp their legs or to stand in water to avoid being bitten. Female stable flies lay their eggs in spoiled organic matter (bunk feeders, winter feeding sites, hay piles, compost piles) and complete their life cycles in 14-24 days depending on the weather.
Horn flies cause irritation, blood loss, decreased grazing efficacy, reduced weight gains, and diminished milk production. Horn flies can cause decreased weight gain in cattle and calf weaning weights can be 4-15 percent lower. That’s 15 to 75 lbs. Female face flies cause irritation to eye tissue and are one of the main mechanisms for pinkeye to spread between animals. Pinkeye is a highly contagious extremely painful inflammation of the cornea and conjunctiva of cattle which can cause blindness if left untreated. Stable flies cause decreased weight gain due to the irritation and decreased time grazing. Studies have shown a reduction in average daily gain of .44 lbs per head with animals which received no treatment.
The major trick to effective fly control is utilizing a method or methods that will continue fly control for the duration of the fly season. There are lots of effective methods to killing flies put a good fly program will commonly use multiple methods to give cows coverage all season long.
Sprays (typically a pyrethroid or organophosphate) are very effective at controlling horn flies and face flies, but they only provide control for 2-4 weeks. Sprays will need to be reapplied to all cows every 3-4 weeks to significantly decrease fly numbers.
Avermectin pour-ons (Ivermectin, Cydectin, Eprinex, Dectomax) are an effective way to control horn and face flies while also deworming cattle. However, they are again only good for 2-3 weeks and repeated use of dewormers could lead to resistant worm populations.
Oral larvicide or IGR’s can help decrease populations by preventing horn, house, and stable fly larvae from developing into adults. However, it is important to ensure steady consumption for the product to be effective. These products should be started 30 days before flies typically emerge and should be continued until 30 days after a killing frost for complete effectiveness. Even then they are commonly not enough to drastically lower fly populations on their own.
Backrubbers and dust bags (again typically using a pyrethroid or organophosphate) are an economical way to reducing horn and face fly numbers if they are placed at a site where all cattle use it and they are always kept charged.
Insecticide ear tags and strips are another route of controlling horn and face fly populations. Don’t be fooled, not all fly tags are created equal. While all tags will probably give great coverage for 4-5 weeks, quality fly tags provide 3-4 months of fly control. Most tag programs require two tags per adult cattle and one tag per calf for optimum control. A common misconception is that fly tags ward off flies, actually they are spreading insecticide over the cow which then kills the flies that come in contact with it. This is why only tagging calves will provide very little fly control as the flies are still able to survive insecticide free on the cows.
Finally, you’ll notice very few of these methods were highly effective at controlling stable flies. Because stable flies concentrate on the legs of animals it is very difficult to get insecticide coverage where the flies are. As a result the best method for controlling stable flies is destruction of their breeding ground. Clean-up of wasted grain and hay at winter feeding sites will greatly reduce stable fly numbers. It is important that we keep our faculties and pastures clean and well maintained.
So tell me can you tell the difference that two pastel earrings make for the life of a cow?
And are you taking care of His creation?
So go visit your veterinarian and go tell the fly….Shoo fly don’t bother ME or my cattle herd!
Until next time,