Posted: 30 Apr 2020 01:22 PM PDT
Part 1 of "Fly Season is
Coming!" (or for many, is here), there could be no other fly worthy of
being first than the stable fly. Not only is it the FIRST biting fly to emerge
for the year (or if you live in the south, stay active all year) it is also a
nasty biter that will take advantage of any bloodmeal it can get.
The stable fly is the most
significant pest of livestock in America; because of its painful bite and blood
feeding behavior, cattle self-inflict stress and injury trying to escape
attack. The impact of the stable fly is noticeable with populations of
more than 20 flies per animal, which can adversely affect animal health and
significantly lower income for livestock producers. Evidence shows that
heavy infestations of stable flies on beef cattle have reduced weight gain by
25 percent and, in dairy cattle, have decreased milk production by 10 to 20
percent.
To suppress stable flies effectively and economically, it is important to:
The stable fly is the most
significant pest of livestock in America; because of its painful bite and blood
feeding behavior, cattle self-inflict stress and injury trying to escape
attack. The impact of the stable fly is noticeable with populations of
more than 20 flies per animal, which can adversely affect animal health and
significantly lower income for livestock producers. Evidence shows that
heavy infestations of stable flies on beef cattle have reduced weight gain by
25 percent and, in dairy cattle, have decreased milk production by 10 to 20
percent. To suppress stable flies effectively and economically, it is important to:
§ Be
able to identify them properly;
§ Understand
the insect’s life cycle; and
§ Use a
combination of control strategies.
Identification
The stable fly, Stomoxys calcitrans, looks like the house
fly, but it is smaller (1⁄4 inch). Unlike the house fly, stable fly mouthparts
resemble a bayonet that can easily be seen protruding from the head. The
stable fly differs from the housefly in that it depends on blood as food and
has an extremely painful bite. Stable flies primarily attack the legs of
livestock and the ears of dogs.
An animal’s reaction to being attacked by stable flies consists of
objectionable behavior such as stomping and kicking their legs, this makes it
difficult to milk dairy cows. Unrestrained animals will typically bunch
together when attack, causing an increase in heat stress.
Biology
and habitat
The stable fly has a complete life cycle with egg, larval
(maggot), pupal and adult stages. Populations can increase quickly: Under
optimal conditions, the egg to adult cycle is about 3 to 4 weeks; therefore
several generations can develop each year. A female stable fly lives for
3 to 4 weeks and lays 500 to 600 eggs during its lifetime.
The eggs are typically laid in wet straw, wet hay bales or in
other decomposing vegetation mixed with urine and feces produced by the
animals.
Management
To suppress stable fly populations efficiently, producers should
use an integrated pest management (IPM) approach. IPM relies on three tactics
for successful suppression of an insect pest: cultural, biological and
chemical.
Cultural control: Cultural control methods
involve manipulating the environment to reduce insect pest populations. The most
economical and effective method for suppressing stable fly populations is
sanitation.
In confined animal facilities, a top priority should be to
eliminate stable fly breeding sites as often as possible. To do this, remove
and spread decomposing vegetation or bedding material that has become mixed
with urine and feces. Spreading the bedding will allow the material to dry
faster and prevent colonization by the stable fly.
Another tactic for confined animal areas is to design the stalls
to allow for complete manure removal and drainage. Cleaning out the wet feed
remaining in the ends of troughs should be done weekly because the wet feed
serves as a breeding site for flies.
For small to moderate fly populations of adult flies, sticky
traps and other mechanical methods, when combined with sanitation, are
effective in confined areas. However, sticky traps will not substantially
reduce fly numbers if used alone. Sticky traps should be changed weekly because
they become coated with dust or “saturated” with flies.
Spreading decomposing vegetation (unused hay) should also be
implemented for range or pasture cattle. Throughout the year, hay bales are
often provided as supplemental feed for cattle. Over the course of the winter,
the sites where hay bales have been placed become ideal stable fly breeding
areas. Using hay rings will help to reduce stable fly populations in the
field/pasture by reducing the amount of wasted hay trampled into the
soil. Also, moving the feeding site regularly reduces the accumulation of
wasted hay at a site and eliminates breeding sites. Spreading the
accumulated wasted hay, will help dry out the site and prevent continual stable
fly breeding.
Sticky Traps: The use of sticky traps
provides a non-chemical approach to controlling stable flies, both males and
females. The sticky traps are attractive to the adult stages as a resting
location during bloodmeal digestion but prevent the stable flies from leaving.
These traps can be used at any number of facilities but are best placed out of
reach of animals.
Olson Biting Fly Trap
Knight Stick trap
Biological control: This IPM tactic uses
natural predators (fire ants), parasites (like the wasp Spalangia sp.)
or pathogens (Bacillus thuringiensis) to suppress pests.
The parasitic wasp, Spalangia sp., is available
commercially. The wasp lays an egg into the pupa of the stable fly. The
immature wasp feeds on the pupa, eventually killing the pupa. The wasp
develops into an adult and emerges from the pupa to start the cycle again.
At this point, there is no clear answer to the effectiveness of
using parasites to reduce fly populations. Chances for success are
greatest when coupled with waste and water management, and chemical control as
needed. Chemical controls should be limited to sprays or other
application techniques that will not come in contact with breeding sites and
kill the parasites. Wasp releases have to be conducted on a set schedule
and are needed each year; do not count on establishing a population on your
farm. Wasps may supplement an integrated program based on sanitation but
are unlikely to provide adequate control when numerous breeding sites are
available.
Chemical control:
If a stable fly problem persists, an insecticide can be used.
Many compounds are available for suppressing adult and larval stable fly
populations. Always read the pesticide label in its entirety before making any
applications.
Animals can be treated as needed with sprays containing
permethrin (Catron, GardStar, Permectrin II, Permethrin and Tengard), Ravap® EC
(23% tetrachlorvinphos) and Vapona® EC (40.2% dichlorvos). Residual wall
sprays such as Atroban® 11% EC (permethrin), Demon®WP
(cypermethrin), Ravap®, and Vapona® can
be applied to surfaces where the insects rest. These products can be used in
backpack or truck sprayers for range or pasture cattle or used in misters daily
on dairy cattle for protection against stable fly feeding. Brahman and
Brahman cross cattle should not be treated due to hypersensitivity to
organophosphates. One day withdrawal is required for beef cattle sprayed
with Vapona®.
Many premise products are available (Annihilator®, Atroban® 11%
EC, Brute®, Demon® Max, Durashield®, Elector® PSP, GardStar®, Grenade®,
Permectrin II, permethrin, Rabon® 50 WP, Ravap®
EC, Tengard®, and Vapona®) that can be sprayed around a livestock
facility and on side walls that are used as resting sites for fed stable
flies. Always follow product labels for conducting premise spray
applications.
Thanks,
Blayne Reed
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