Controlling Flies with Feed-Through Additives

Hereford young beef stocker acctle
Should you use Rabon, ClariFly or Altosid?  The answer depends on what is being fed and where your animals are housed.  Here is a breakdown of the types of feed-through fly control: 


Sweetlix Rabon Blocks
Animal Location Pasture Confinement Pasture
Targeted Fly Species Horn, Face, House, Stable House, Stable, Face, Horn Horn
Effective Weight 1100 1000 lb. 1400 lb.
Safe for Birds, Fish, Mammals No Yes Yes
Safe for Dung Beetle Larvae Yes No Yes
Season of Use 30/30* 30/30* 30/30*
 Sheep & Goats Sweetlyx Rabon Blocks Sheep Mineral w/ClariFly 50# Contains copper - not for sheep
 Equine Sweetlyx Rabon Blocks SimpliFly 50#, 20#, 10#, 3.75#) Not approved
 Cattle Sweetlyx Rabon Blocks ClariFly pack for Milk Replacers Traditions Mag-O-Min Alt
    HerdFirst Milk Replacer  Right Now Gold Min Alt
    ClariFly Larvicide to add in all feeds Mol Min Tub w/Altosid
      Beef Hi Mag Min ALT 50#
      Wind n Rain Hi Mag Alt
      Wind n Rain Hi Mag Availa4 Tub
* Feed 30 days prior to last frost in spring and 30 days after last frost in fall for best results.



Sheep flock            Young cattle on pasture
  Confinement, Barns & Lots or Pastures, Woodland, and Grazing Systems


Which product used will depend on the fly challenges you have.  If your cattle spend most of their time on pasture and are challenged with horn flies, Altosid IGR products are convenient. Horn flies account for neary 80% of fly issue with livestock and cost the cattle industry $1-$1.5 billion a year. The Mill has multiple mineral premixes in granular or tub form to choose from for cattle.

If livestock are in concentrated feeding areas and smaller lots with face flies and stable flies on legs, ClariFly mixed in feed may be a better option.  Starting a month prior to last spring frost and continuing a month after the last frost in the fall will provide the most effectiveness, however, you can still have success feeding an IGR or larvicide even if you do not start 30 days early.  In both situations, the best control will be achieved with multiple fly control strategies during the heat of the summer.

The mode of action for both products is to pass through the digestive system into manure.  When adult flies lay eggs in the manure, the larvae cannot develop into adult flies.  The interruption in the fly life cycle can provide excellent control of adult fly populations.

ClariFly is also available to mix into milk replacer for calves and does an excellent job of minimizing flies in calf and heifer pens. ClariFly is safe to use for sheep, goats, swine, horses, cattle, etc. to stop flies from developing into adults.

Sweetlix Rabon Blocks have a different mode of action. They contain an organophosphate insecticide that is a cholinesterase inhibitor.  Consult a vet before using with debilitated, aged, breeding, nursing or pregnant horses. It is safe to use for most livestock and horses and prevents development of larvae of all 4 types of flies. Use 1 block per 5 head of horses or cattle to provide the correct level of insecticide and selenium.

Horse wearing fly mask and sheet on green  summer pasture


Controlling fly larvae from developing is just 1 step in reducing fly populations.  Sanitation, proper nutrition and health practices as well as feed management are all essential to keeping animals healthy and comfortable while keeping bugs at bay!  Using other fly control measures such as spray, dust or oil insecticides to control adult flies may be necessary at times. Other fly reduction measures include bait stations, strong air circulation with fans, and sheets and masks for horses.  Keeping areas clean from manure, tall weeds, feed and wet bedding will help keep flies in check too.




Looking for advice or a specific product for controlling flies? Reach out to our Livestock Product Manager, Karen Holloway at or The Mill's Equine Manager, Michelle Jennings at

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