The little horn fly is one of the most profit robbing pests for us here in NC. The pestilence is costly either to the herd’s production or to the producer’s pocket. It’s best to confront the problem head-on than to take your chances and watch those flies take weight off your cattle.
To CONTROL rather than to eliminate the horn fly is the GOAL. To think that you will completely eliminate these flies on your cattle and that maybe they won’t be too bad this year is delusional.
When you visualize the horn fly cycle, then it’s easy to understand why they are so hard to handle. They show up as soon as it begins to turn warm. If you didn’t control them last year, they will more than likely be worse this year.
How the Horn Fly Works:
Both male & female horn flies bite cattle and will take 20-40 blood meals each day. The female searches for fresh manure that is less than 10 minutes old & lays her eggs. Just that one female horn fly can produce 400 eggs in her lifetime. From egg to adult is less than 9-12 days. With that short life cycle, you could have more than 10 generations per year. Hence, the reason why these flies can develop an insecticide tolerance. What worked last year may not work again this year. We are having to constantly change our ammunition.
Here are your options to control horn flies:
Self-Applied Treatments (back-rubs/dust bags, IGR mineral, bolus)
Sprays & Pour-ons
(Other options, like fly traps/vacuums & automated spray designs, maybe I will discuss in another post.)
Choosing just one of the above will not do the job.
And if your flies are sticking with the herd even after you have sprayed or tagged, you are likely to have strains resistant to the synthetic pyrethroid and organophosphate insecticides.
Here’s a 3 Way Approach to control these horn flies:
Feeding mineral is essential to production, so why not let the cow do her part to help with fly population. Purchase the IGR mineral in February so you have it ready to put in the mineral feeder right before 60 degree weather. If the winter is mild like this last one, you will wish you had that IGR mineral riding in the back seat!
Fly Tags are money well spent IF you know which chemical the horn flies on your farm aren’t resistant to. Work those cattle before it gets miserable outside and you will drive through your herds with a smile instead of getting those nasty looks from the cows while they are stomping and swishing.
Sprays & Pour Ons are the best way to kill the current population. You can do the mineral and tags, but those 2 things alone will not resolve your present situation. This is actually my first defense early in the season. Work the cattle early in the spring and before fly breeding gets out of hand.
Using the 3 options above will get you well ahead of the game.
Here’s my 3-way strategy to control horn flies on our cattle this summer:
IGR mineral (Renaissance)
Ravap EC spray for early low threshold control (details here) + Cydectin Pour-on Dewormer – (deworm + fly control for approx 20 days)
Y-Tex XP820 fly tags (details here) contains abamectin, a new effective insecticide
NEW PRODUCT: The XP820 tags also come in strips that instead of piercing the ear, you just hang the strip on the id tag. Last year, when it was time to remove the old fly tags, instead of completely removing the pierced side with the fly tag, I cut right below the stem, leaving the button in place on the ear. The reason behind that was so this year, I could use 2 fly strips on the cows. One strip hung on the id tag and the other strip hung on the button from last year. This way, I never have to pierce that cow’s ear again.
Hanging 2 fly strips on the cow’s ears were so much simpler, quicker, & the cows love me for not piercing their ears again and again.
I simply used a wipe to clean their id tag & placed 2 strips, one on each ear. Job done! (Strips will hang on the buttons & the Z-tags. You might find 1-2 strips where the cows rub them off, but the retention rate is still high enough for me not to loose sleep.)
The 3-way plan above should be very effective for the fly season. Next year, you will need to change your fly tag.
The IGR mineral and Cydectin Pour-on will continue to be effective because they use a different mechanism against the horn fly.
**Remind yourself how much stress there is to work the cattle when it’s so hot and humid. Also, keep in mind that horn flies impact your herd in many ways:
decreased milk production
decreased libido in bulls
decreased weight in calves
transfer of disease.
Horn flies aren’t the only flies that give our cattle grief but the Ravap EC spray should help fight all other visitors that temporarily show up to eat our beef.
*Other Key Points:
use 2 tags per adult
remove fly tags at end of season (October usually)
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Other great links to learn more about horn fly control control & products: