Stable flies are slightly smaller than
Stable flies have dark stripes on
their back and a checkerboard-like pattern on the top of their abdomen.
Stable flies have a long, sharp
proboscis. The bite feels like a stab by a pin in the skin.
OUCH! Stable fly acquiring its next meal.
The house fly and stable fly are similar in size, color and general
appearance; they are often referred to as barnyard flies. On closer
examination, these two flies are quite distinct in appearance, feeding
habits and in the ways they annoy livestock, people, and pets.
A distinguishing feature, visible to the naked eye, that separates
the two species is the distinct stiletto-like proboscis of the stable
fly which extends forward beyond the head. This sharply pointed beak is
used to pierce the skin and draw blood. The house fly cannot bite since
it has sponging mouthparts.
Adults: Both male and female stable flies feed on blood and are
persistent feeders that cause significant irritation to their host.
Adults are 7 to 8 mm (1/4 inch) long and resemble house flies. A
"checkerboard" appearance of the top of the abdomen and the
stiletto-like proboscis will separate this species from adult house
Eggs: Stable fly eggs are about 1 mm long and are an off-white
color. Females deposit clusters of eggs containing up to 50 eggs.
Several such clusters of eggs will be deposited during the life of a
female fly and a single female can lay up to a thousand eggs during her
Larvae: Stable fly larvae have a typical maggot shape. There are
three larval stages. The last stage larva is about 10 mm long and is a
cream white color.
Pupae: After the third stage larva completes feeding it shortens,
hardens and darkens in color. The chestnut brown pupa is 6 to 7 mm long.
Stable fly pupae are very similar in appearance to house fly pupae and
are difficult to distinguish since, in their natural habitat, they are
usually mixed with house fly pupae.
Stable flies will feed on blood from practically any warmblooded
animal, including humans, pets and livestock. During periods of high
stable fly activity, humans can be severely annoyed and this insect has
been called "the biting house fly." Individual flies may feed
more than once per day. Peaks of feeding activity commonly occur during
the early morning and again in the late afternoon. Stable flies prefer
feeding on lower parts of the hosts such as the legs. Both male and
female stable flies feed on blood, and the female requires blood meals
to produce viable eggs. Females deposit their eggs in a variety of
decaying animal and plant wastes, but are rarely found in fresh manure.
This fly prefers excrement mixed with straw, soil, silage or grain but
are also found in wet straw, hay, grass clippings, other post harvest
refuse and poorly managed compost piles. Large round hay or straw bales,
where contacted by moist soil, may serve as larval development sites.
Larval development requires 11 to 21 days, depending on environmental
conditions. Mature larvae then crawl to drier areas to pupate. The pupal
period varies from six to 26 days depending on temperature. The entire
life cycle from egg to adult is generally completed in three to six
Stable flies are active during the summertime in North Dakota and are
the most important pests of dairy and feedlot cattle in the state.
Stable flies prefer to feed outdoors and rarely are found feeding or
resting indoors. These flies are strong fliers and dispersion from one
livestock facility to the next is common. They remain active into
October, but the larval development slows as autumn temperatures
decrease. At temperatures near freezing, larvae survive and continue to
develop slowly in habitats such as piled silage or manure where
fermentation generates heat.
Applications of residual insecticides to premises are frequently
used to control both house and stable flies. Longer residual
insecticides provide control for an extended period when sprayed onto
sites where the adult flies congregate. Such places as fences, sides of
buildings and inside and outside of animal stalls may be potential day
or night resting sites for these flies. Observation of a barnyard
situation will rapidly tell the favored resting sites for flies. Flies
contact the insecticide when they land on the treated surfaces. Residual
insecticides are effective because they control flies over an extended
period of time and even will kill flies that emerge after treatment.
Knock-down sprays are effective in killing adult flies present at
the time of application. The chemicals used for these applications are
short residual insecticides having a quick knock-down and high contact
toxicity. Several types of spray or fogging apparatus may be used for
these applications. Wind velocities should be low at the time of
application and the droplet or particle size should be small to ensure
drift through the feedlot or dairy. This method requires less time for
application but has the disadvantage that it will only kill flies
present at application.
Other methods of fly control such as baits, electric grids and
traps may have some limited use for house fly control but are
ineffective for the blood-feeding stable fly.