Biology The stable fly is a very serious economic biting fly pest for confined cattle throughout the US and is becoming a serious pest for pastured cattle as well. Both sexes suck blood and prefer to feed on the lower body and legs of cattle. If enough flies are present, this may lead to reduced weight gains or milk production in dairy cows. Annual economic loss in North America due to stable flies is estimated at nearly $1 billion. Stable flies breed in many wet places, including old manure, decaying feed, calf bedding, compost, silage, etc. Stable flies will also disperse long distances from where they were bred and become significant pests of humans. The generally agreed upon economic threshold for cattle is 5 flies per leg, at which point beef cattle show reduced weight gains. Similar effects likely occur in milking cows. Management of stable flies is principally through improved sanitation and manure management. When sanitation measures are not enough to control adult populations, application of insecticides to premises or animal quarters may be necessary (see "Fly Control" section). There are a few on-animal chemical control options, listed below.
- diazinon ear tag (Patriot)-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.
- permethrin ear tag (GardStar Plus)-Apply one tag per ear on all animals when flies first appear in spring. Remove before slaughter.
- zeta-cypermethrin 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.
- dichlorvos spray (Prozap Beef & Dairy RTU) Apply 1-2 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.
- permethrin spray (Atroban 11% EC)-Dilute 1 quart per 50 gal water. Spray 1 to 2 qt per animal. Treat once every 2 weeks as needed.
- permethrin RTU pour-on & spray (Permectrin S)-Use undiluted in a mist sprayer. Apply 0.5 oz per 100 lb body weight to neck, face, back, legs, and ears. Repeat treatment as needed but do not exceed 5 fl oz during any 14-day interval.
- permethrin spray (Durvet 10%; Prozap Insectrin X Fly Spray 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.
- pyrethrins (EverGreen Pro 60-6) at 2 to 3 fl oz/gallon of water. Apply 1 qt per adult animal. Wet hair thoroughly. Repeat as needed.
- pyrethrins spray (PyGanic Livestock & Poultry Insecticide)-Dilute at 9 to 14 oz per gal water. Apply 1 qt per adult animal to thoroughly wet hair. Repeat treatment each week as needed. Do not exceed 1 treatment per day. This organic product is OMRI listed.
- pyrethrins/permethrin aerosol (Pystol Farm & Dairy Aerosol)-Thoroughly spray entire animal for 2-4 seconds from approximately 2 ft away as it is being released to pasture. Do not spray directly toward animal's face.
- rosemary, peppermint oils spray (Essentria IC3) Mix at 30 to 90 ml (1 to 3 oz) per gal mineral oil. Spray directly on animal in amounts to sufficiently cover. Avoid contacting teats with spray unless teats are washed and dried before milking. Apply at least 20 minutes before milking of after milking is complete.
- permethrin backrubber or self-oiler (Gardstar 40% EC)-Dilute at 118 ml (4 oz) per 10 gal mineral oil or diesel oil. Keep rubbing device charged. Results improve with forced daily use.
- pyrethrins 1% dust (Evergreen Pyrethrum Dust)-Directly apply 2 oz to animal with shaker can or other device. Can be applied through dust bag placed in area where cattle congregate or pass through. This organic product is OMRI listed.
- zeta-cypermethrin dust (PYthon)-Directly apply 2 oz per animal. Make sure to apply dust to legs. Repeat as needed but not more than once every 3 days.
- diflubenzuron feed supplement (Clarifly 0.04%; JustiFLY 0.67%)-Prevents development of immature forms in manure of treated animals. 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 (Clarifly elim-A-fly Add-Pack 0.16%; JustiFLY 0.16% Milk Replacer Product)-Prevents development of immature forms in manure of treated calves. 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.
- tetrachlorvinphos mineral block (Sweetlix Rabon)-Feed free choice, 1 block for 5 head of cattle.