Managing Stable Flies
on Livestock and Around
Livestock Facilities
by Gregory Johnson, Professor of Veterinary Entomology, Montana State
University- Bozeman
MontGuide
Stable flies are worldwide pests of domestic livestock, wildlife and people.
This Montguide describes this pest, its biology, and management approaches
to reduce economic losses associated with these biting flies.
MT201111AG New 11/11
The life cycle, consisting of egg, larva, pupa and adult,
domestic livestock, wildlife and people. Native to Europe can be completed in about three weeks during the summer
months. Eggs are deposited in wet, decaying organic
and Africa, it was probably introduced into North
material such as trampled hay where big bales are fed,
America during colonial times. Other common names
manure mixed with straw or other bedding, vegetable
for this biting fly are the dog fly because they pester
or fruit matter, aquatic vegetation on lake shores, piles
dogs; the beach fly because of outbreaks on recreational
of grass clippings, waste silage or
beaches; and the biting house fly
feed in feedlots or compost heaps.
because it superficially resembles
Manure piles are not favorable sites
the house fly. In the Midwest and
for stable fly oviposition. A female
northern Great Plains they are
will deposit 35 to 80 eggs at one
often abundant around confined
time deep in the organic material.
animal facilities such as dairies
Ten or 11 egg-laying periods occur
and feedlots. Both sexes require
during the life of the fly (four to six
animal blood for growth and
weeks). The eggs hatch in one to
energy and female flies use blood
three days, and the larvae (maggots)
for egg development. Their painful
feed on the decaying organic
and annoying bites often result
material and develop through three
in livestock bunching together
instars. At the last instar, the larva
to avoid attack, moving to areas
moves to a drier environment and
with lower fly activity, and flychange to a reddish, barrel-shaped
repelling behaviors such as tail
pupa after which the formation of
flicking, foot stomping, and head
the adult fly occurs.
tossing. These defensive behaviors
negatively affect meat and milk
After the adult emerges, it is
production. This Montguide
ready to feed and mate. Both
FIGURE 1. Top view of an adult stable fly.
Note longitudinal stripes on thorax (back) and
describes the stable fly, its biology
sexes feed on blood and generally
proboscis protruding bayonet-like in front of
and management approaches to take one blood meal per day.
the head.
reduce economic losses associated
They usually attack the front legs,
with these biting flies.
belly and sides of cattle or horses. On smaller ruminants
(goats, sheep, hogs) and dogs, they attack the legs, head
General Biology and Life Cycle
and ears. An individual fly is on the host only as long as it
The stable fly is about the size of a house fly (one-quarter
takes to obtain a blood meal, usually two to five minutes.
to three-eighths inch long), but darker in color. The
Females usually begin laying eggs five to 10 days after
abdomen has dark irregular spots while the top of the
emergence. Stable flies are daytime feeders and generally
thorax has four distinct, dark longitudinal stripes. Unlike
will not enter buildings to find a host. During the heat
the house fly, the stable fly is a blood feeder and the
of the day, they can be found resting in vegetation,
proboscis (mouthpart) protrudes bayonet-like in front of
on fences or on the shady side of buildings frequently
the head (Figure 1).
STABLE FLIES ARE WORLDWIDE PESTS OF For More Online MontGuides, Visit www.msuextension.org
adjacent to their food or egg-laying sites. On windy days,
they can be found on the leeward side of buildings. Stable
flies are inactive at night and roost on fences, buildings,
trees and bushes.
In temperate regions of the U.S., stable flies overwinter
below the frost line as slowly developing larvae in organic
matter. As temperatures warm in the spring, they migrate
closer to the surface, pupate and complete development.
Adult fly populations normally build up slowly in early
summer and peak in July and August.
FIGURE 2. Four stages of the stable fly - egg, larva, pupa and
adult. (Photo by Jim Kalisch, University of Nebraska.)
Animal reactions and economic losses
Livestock attacked by stable flies will group together in
a tight bunch to reduce the intensity of fly attack. Cattle
will move to areas such as a windy hill top that may have
fewer flies or stand belly deep in water to avoid biting
flies. Such evasive behaviors (grouping and moving) will
alter pasture utilization by grazing cattle and in turn
affect animal production. Fly-repelling responses such as
tail switching, foot stomping, skin twitching and head
tossing are attempts to dislodge the flies and the frequency
of these activities increases as fly densities increase. The
energy expended fighting flies negatively affects meat
and milk production. Nebraska studies by Campbell et
al. (1987, 2001) have shown stable flies responsible for
decreased weight gains from 0.2 - 0.4 pound for feedlot
cattle. Weight losses of a similar magnitude were recorded
for grazing steers.
Stable flies are known to severely attack the ears of
dogs. Skin lesions from stable fly bites are commonly
observed on the tips of ears of dogs being attacked by
stable flies. Intense feeding can cause scabbing on legs
of horses. While previously not known to feed on birds,
stable flies were observed attacking juvenile white pelicans
infected with West Nile virus (Johnson et al. 2010).
Stable Fly Management
FIGURE 3. Accumulation of feed along feed bunk where stable
flies egg laying and development can occur. (Note: this particular
diary routinely cleaned up spilled feed and stable flies were not a
problem. Photo by Greg Johnson.)
FIGURE 4. Blood engorged stable fly on a West Nile virusinfected pelican at Medicine Lake, MT. (photo by Greg Johnson)
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Controlling stable flies around animal confinement
facilities starts with good sanitation. This includes cleaning
up spilled feed, fixing leaky water tanks, providing good
drainage from the pens, maintaining sloping mounds,
cleaning pens, scraping behind feed bunk aprons and
restricting pen size to create better drying conditions.
Depending on the number of cattle in a facility, removal
of larval habitat (moist manure, decaying plant matter,
spilled feed) may be necessary on a weekly basis. Removal
of the larval media breaks the life cycle of the stable fly.
The waste material can be thinly spread to dry; the dried
material is unattractive for egg laying and larvae cannot
complete development in dry media.
Considerable research has been conducted on
biological control of stable flies with parasites. Small
parasitic wasps, called pteromalids, parasitize stable fly
and house fly pupae. Commercial insectaries have many
of these species for sale. Some researchers claim substantial
increases in parasitism rates following releases of these
parasites, whereas other researchers found that parasitic
wasps did not provide adequate control at release rates
considerably higher than recommended (Thomas and
Skoda 1993). This research was conducted at feedlots and
dairies with confined cattle.
Insecticides recommended for stable fly control are
listed by application method on page 2. Stable fly control
with insecticides may be achieved by treating premises in
and around beef and dairy facilities or directly treating
livestock. As premise sprays, diluted insecticide is applied
to vertical and overhead surfaces of livestock facilities
where flies may congregate. It is often best to spray in
the early morning when flies are still resting on these
surfaces. Insecticides mixed for spraying premises should
not be applied to livestock. Read the insecticide label for
treatment information.
A number of insecticides and application methods
are registered for on-animal use. Application methods
include animal sprays, ear tags, dust bags, pour-ons and
feed supplements. Animal sprays, which cover the lower
portion of the animal’s body, generally provide the best
stable fly control, although the effectiveness is short-lived.
Applicators should be aware that “aids in control of stable
flies” rather than “controls stable flies” is stated on many
of the insecticide labels for ear tags, dusts and pour-ons.
Insecticides labeled “aids in control” generally provide less
than satisfactory results.
References
Premise and Animal Spray
(Labels of these insecticides state “controls stable flies.”)
Atroban EC (11% permethrin)
Elector (2.46% spinosad) – premise spray only
GardStar EC (40% permethrin)
Permectrin II (10% permethrin)
Vapona Insecticide Spray (1% dichlorvos)
Ear Tags
(Labels of these ear tags states “aids in control of stable flies.”)
Avenger Patriot GardStar Plus Python Warrior (30% endosulfan)
(40% diazinon)
(10% permethrin)
(10% zeta-cypermethrin)
(30% diazinon, 10% chlorpyrifos)
Insecticide Dust
(Label states “aids in control of stable flies.”)
Python Dust (0.075% zeta-cypermethrin)
Pour-ons
(Label states “aids in control of stable flies.”)
Brute (10% permethrin)
Oral Larvicide
(Label states “prevents adult emergence of stable flies.)
ClariFly Rolyx Pro Campbell, J., I. Berry, D. Boxler, R. Davis, D.
Clanton, and G. Deutscher. 1987. Effects
of stable flies (Diptera: Muscidae) on weight
gains and feed efficiency of feedlot cattle.
Journal of Economic Entomology. 80:
117-119.
Campbell, J., S. Skoda, D. Berkebile, D.
Boxler, G. Thomas, D. Adams and R.
Davis. 2001. Effects of stable flies (Diptera:
Muscidae) on weight gains of grazing
yearling cattle. J. Econ. Entomol. 94: 780783.
Johnson, G.D., N. Panella, K. Hale and
N. Komar. 2010. Detection of West Nile
Virus in Stable Flies (Diptera: Muscidae)
parasitizing Juvenile American White
Pelicans. Journal of Medical Entomology.
47: 1205-1211.
Thomas, G.D. and S. R. Skoda. (eds.) 1993.
Rural Flies in the Urban Environment.
North Central Regional Research
Publication No. 335. Institute of
Agriculture and Natural Resources,
University of Nebraska.
(0.67% diflubenzuron)
(2.0g rabon per lb.)
Carefully read and follow the insecticide label concerning the application of any insecticide
to cattle and precautions concerning calves and lactating dairy cattle. Every attempt was
made to include all products commercially available for stable fly control. Omission of any
product was unintentional. Products are not listed in order of preference or superiority for
stable fly control. Due to constantly changing labels, laws and regulations, MSU Extension
can assume no liability for the suggested use of chemicals contained herein. Pesticides must be
applied legally, complying with all label directions and precautions on the pesticide container
and any supplemental labeling and rules of state and federal pesticide regulatory agencies.
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File under: Agriculture and Natural Resources
(Pest Managment)
New November 2011 300-1111SA