Dairy cattle-Horn fly

Haematobia irritans

Biology The horn fly was introduced into the United States during the 1800s and spread rapidly across North America. Females lay eggs in fresh cattle manure, which is where immature forms complete development. During warm weather, the life cycle of a horn fly is 10-20 days; there are many generations of flies each year. The first flies appear in June or earlier; flies disappear with hard frosts in fall. Both sexes suck blood from cattle and other animals. Horn flies are usually seen on animals' backs and sides. If enough flies are present, this can lead to reduced weight gains or milk production of cattle. However, cattle can tolerate a low density of horn flies without measurable losses. The generally agreed upon economic threshold is 200 horn flies per animal.

Management-mechanical control

  • fly vacuum (Spalding Cow-Vac)-Animals walk single file through compartment, and vacuum removes flies to a removable bag for disposal. Works best on grazing dairy, placed where cows return to barn. Requires electrical supply.

Management-chemical control

Ear tags

  • abamectin/piperonyl butoxide ear tag (XP 820)-Apply one or two tags to all animals in herd when flies become a problem in spring. Remove tags at end of fly season or before slaughter.
  • beta-cyfluthrin ear tag (Cylence Ultra)-Apply one tag to each ear of all animals older than 3 months when flies appear. Remove tags at end of fly season or before slaughter.
  • diazinon ear tag (OPtimizer)-Apply one tag to each ear of all animals older than 3 months. Do not use on lactating dairy cattle. Remove before slaughter.
  • diazinon/chlorpyrifos ear tag (Warrior)-Apply one tag to each ear of all animals older than 3 months when flies appear. Do not use on lactating dairy cattle. Remove before slaughter.
  • diazinon/coumaphos ear tag (Corathon)-Apply one tag to each ear on all mature animals when flies appear. One ear tag per calf. Do not use on lactating dairy cattle. Remove tags at end of fly season or before slaughter.
  • lambda-cyhalothrin/piperonyl butoxide ear tag (Saber Extra)-Apply one tag to each ear on all animals when flies appear in spring. Do not use on lactating dairy cattle. Remove tags in fall or before slaughter.
  • lambda-cyhalothrin/pirimiphos-methylear tag (Double Barrel VP)-Apply one tag to each ear on all animals in herd when flies appear in spring. Do not use on lactating dairy cattle. Remove tag in fall.
  • permethrin ear tag (GardStar Plus)-Apply one tag per ear on all animals when flies first appear in spring. Remove before slaughter.
  • pirimiphos-methyl ear tag (Dominator)-Apply one tag per ear on all animals when flies first appear in spring. Do not use on lactating dairy cattle. Remove tags in fall.
  • zetacypermethrin/piperonyl butoxide ear tag (PYthon MagnuM)-Apply one tag per head of all animals at least 3 months old when flies appear in spring. Remove tag at the end of fly season or before slaughter.
  • zetacypermethrin/abamectin ear tag (Tri-Zap)-Apply one tag per ear of all animals. Remove at end of season or before slaughter.

Pour-ons, sprays

  • coumaphos (Co-Ral Fly & Tick Spray)-Mix 1 quart per 50 gal water. Spray to complete wetting to run-off. Treat no more than 6 times/year. Do not apply less than 10 days apart.
  • cyfluthrin pour-on (CyLence)-See label for dosing instructions. Pour along top of back and head of cattle of all ages. Repeat as needed but no more than once every 3 weeks.
  • dichlorvos spray (Vapona)-Dilute 1 gal in 50 gal water (1% solution) and apply up to 2 fl oz of solution per animal as a fine mist spray. Do not wet hide. Do not treat calves under 6 months of age. One day meat withdrawal.
  • dichlorvos spray (Prozap Beef & Dairy RTU)-Apply 1 to 2 oz per adult animal as a mist to wet hair. Use proportionately lower rates for smaller animals. Do not exceed 2 oz per animal per day. Do not soak skin or wet hide.
  • diflubenzuron/permethrin pour-on (Lice-Ban)-Apply 3 mL per 100 lb body weight to maximum of 30 mL.
  • permethrin spray (Atroban 11% EC)-Dilute at 1 quart to 50 gal water. Spray 1 to 2 quarts per animal. Treat once every 2 weeks as needed.
  • octanoic acid/nonanoic acid/decanoic acid (Ecovet Fly Repellent)-Apply to hair coat with small sprayer or a cloth.
  • permethrin pour-on (Boss)-Apply at 3 ml per 100 lb body weight. Maximum of 30 ml (1 fl oz) per animal. Retreat as needed but no more than once every 2 weeks.
  • permethrin pour-on (Martin's 1%)-Pour along back line and down face at 0.5 ounce per 100 lb body weight up to a maximum of 5 ounces. Repeat as needed but don't exceed 5 ounces during any 14 day interval.
  • permethrin spray (Gardstar 40% EC) Dilute at 118 ml (4 fl oz) per 25 gal water (0.05% ai). Apply 1 to 2 quarts high pressure spray over body of animal. For low-pressure spray, apply at 118 ml (4 fl oz) to 2.5 gal water; spray to point of runoff.
  • permethrin spray (Durvet 10%; Prozap Insectrin X Concentrate)-Dilute 0.64 oz (normal infestation) or 1.28 oz (severe infestation) per gallon water (0.05%, 0.10%). Spray to thoroughly cover entire animal. Spray lactating cows only after milking is complete.
  • permethrin RTU pour-on & spray (Gordon's)-Apply undiluted along back and down face at 0.5 to 2 fl oz per 100 lb to a maximum of 20 oz. Use as needed but no more than once every 2 weeks.
  • permethrin spray (Prozap Screw Worm Ear Tick Aerosol; Durvet Screw Worm Aerosol)-Spray about 3 seconds on each side. Repeat treatment with flies are troublesome.
  • permethrin/piperonyl butoxide pour-on (Ultra Boss) -Apply at 3 ml per 100 lb body weight. Maximum of 30 ml (1 fl oz) per animal. Retreat as needed but no more than once every 2 weeks.
  • pyrethrins/piperonyl butoxide spray (EverGreen Pro 60-6)-Dilute at 1 to 2 fl oz/gal of water. Wet hair thoroughly. Repeat as needed.
  • pyrethrins spray (PyGanic Livestock & Poultry Insecticide)-Dilute at 5 to 10 oz per gal water. Spray to thoroughly wet hair. Repeat at intervals of 5-12 days or as needed. Do not exceed 1 treatment per day. This organic product is OMRI listed.
  • pyrethrins spray (Evergreen Pyrethrum Concentrate)-Dilute at 1.5 to 3 oz per gal water and apply to wet hair thoroughly. Repeat at 5-12 day intervals or as needed with large fly populations. This organic product is OMRI listed.
  • pyrethrins/permethrin/piperonyl butoxide aerosol (Pystol Farm & Dairy Aerosol)-Thoroughly spray entire animal for 2 to 4 seconds from approximately 2 ft away as it is being released to pasture. Do not spray directly toward animal's face.
  • pyrethrins/piperonyl butoxide spray (Vampyre Misting Concentrate)-Dilute at 4.3 fl oz per gal water (for 0.10% pyrethrins) or 22 fl oz per gal water (for 0.50% pyrethrins). Spray about 3 seconds on each side of animal.
  • pyrethrins/piperonyl butoxide/N-octyl bicycloheptene dicarboximide spray (SSI-50)-Spray animal as it's being released to pasture. Spot treat withers, shoulders, and back where saliva accumulates.
  • tetrachlorvinphos/ddvp spray (Ravap EC)-Mix 1 gal in 200 gal water. Apply as coarse spray, up to 0.5 gal per animal. Apply at least 20 minutes before milking or after milking is complete. Do not treat calves under 6 months of age. Do not treat more often than once a day.

Backrubbers (oil)

  • coumaphos (Co-Ral Fly & Tick Spray)-Mix 4 quarts in 13 gal of no. 2 diesel or fuel oil. Place backrubber where animals congregate or pass through.
  • permethrin (Durvet 10%; Prozap Insectrin X Concentrate 10%; Martin's Stock-Tox X)-Dilute 8 oz in 5 gal oil (0.125%). Keep backrubber charged.
  • permethrin (Gordon's)-Use undiluted. Recharge as needed.
  • tetrachlorvinphos/ddvp backrubber (Ravap EC)-Mix 1 gal in 25 gal approved oil and use in mechanical rubbing device or burlap or rope backrubber. Charge as needed.

Dusts

  • coumaphos dust (Co-Ral 1%)-Suspend bags where cattle congregate or pass through (e.g., milking parlor exit lane) daily. Place bags so they hang 4 to 6 inches below animals' backline. Direct applications of 2 oz per animal may be repeated no more frequently than 10 days apart and no more than 12 applications in 12 months.
  • permethrin dust (several brands, 0.25%)-Suspend bags where cattle congregate or pass through. Place bags so they hang 4 to 6 inches below animals' backline. Direct applications of 2 oz per animal may be repeated as needed but no more than once every 3 days.
  • zetacypermethrin/piperonyl butoxide dust (PYthon)-Apply in dust bag, shaker, dusting glove, or mechanical duster. Suspend bags where cattle congregate or pass through (e.g., exit alley of milking parlor). Place bags so they hang 4 to 6 inches below animals' backline. Direct applications of 2 oz per animal may be repeated as needed but not more often than once every 3 days.

Feed supplements (prevent development of flies in the manure of treated cattle)

  • diflubenzuron feed supplement (ClariFly 0.04%; ClariFly 0.67%; ClariFly 8%; JustiFly 0.67%; JustiFly 8%)- Mix into grain according to label to provide 0.1 mg ai/kg (4.55 mg/100 lb) body weight per day (follow table on label). Start feeding early in spring before flies appear and discontinue when cold weather limits fly activity.
  • diflubenzuron for milk (elim-A-fly Add-Pack with ClariFly 0.16%; JustiFly 0.16% Milk Replacer Product)- Mix daily into milk/milk replacer according to label to provide 0.1 mg ai/kg (0.1 oz elim-A-fly/100 lb) body weight per day. Start feeding early in spring before flies appear and discontinue when cold weather limits fly activity.
  • diflubenzuron mineral tub (Vitalix ClariFly Tub)-Provide free choice with targeted consumption of 1.6 oz per 100 lb of cow per day (~one tub per 15-25 head). Provide before flies appear until end of fly season.
  • (S)-methoprene premix (Altosid IGR Custom - dry 0.4%, 2%, 10.5%; liquid 1%)-Use formulas on label to determine proper amounts to mix with feed or minerals. Begin use 30 days prior to fly season; continue feeding until cold weather restricts horn fly activity.
  • (S)-methoprene mineral tub (Vitalix Mineralix fly tub with Altosid; Purina Wind & Rain mineral tub with Altosid)-Feed free choice with one tub for every 15-25 head of cattle. Place tubs out before flies appear and continue use until cold weather marks end of fly season.
  • tetrachlorvinphos mineral block (Prairie Pride Rabon)- Feed free choice, 1 block for 10-15 head of cattle.
  • tetrachlorvinphos feed supplement (Rabon 97.3; Rabon 7.76)-Include in diet or supplement at 70 mg per 100 lb body weight daily. See Mixing and Use Instructions for additional details.