Flies - which I hope answers some of the questions.
QUICK DRAFT - COMMENTS AND SUGGESTIONS PLEASE.
Ordinary flies are annoying to animals and can worry them enough to decrease
production, but biting and blood-sucking flies that can be a severe problem.
Animals can suffer blood loss, allergic reactions and exhaustion with stress
that causes cattle to bunch together and mill around each other, becoming
dirty, sweaty and smelly which attracts more flies. There are many different
flies in different countries. Find about those that are problems in your
area and do the best you can to control them. Some are described below.
Flies can also spread diseases such as pink eye, calf scours and mastitis,
and can infect humans. In some countries farmers give up grazing because of
flies worrying their grazing animals. Some graze only at night.
Some farmers in some countries house and stall feed their animals solely
because flies pester their grazing animals. I wonder if flies were as bad
before man started farming domestic animals under confinement where flies
breed like flies! I don�t recall a fly problem in the massive Kruger
National Game Park in South Africa at either visit 20 years apart. It is not
always the animals causing the increase, but how man handles animals and
their effluent. Housing cattle with the resulting heaps of manure increases
fly numbers.
I've never seen so many flies around dairies as in North America. In New
Zealand there would not be 1% the number they have. If we had that many our
dairy and health inspectors would close the farm dairy. Australia also has a
lot. However, while in New Zealand flies severely affecting animal
production is not common, I have seen it occur and have suffered it on our
farm in 1956 before silage stacks were covered with plastic film. Flies will
breed in uncovered silage stacks and in the damp soil around them.
South Africa and Australia have similar climates, but in South Africa
farmers don�t hang corks on their hats and don�t salute all day because they
have a lot fewer flies, partly, I believe, because South Africa has millions
of large white cattle egrets and small black tick birds that follow grazing
animals all day and eat insects as they are disturbed. Also South Africans
make an effort to control them with fly traps over their heaps of manure at
barns. See below. (There is trap in this Macintosh Pages document that I can
email in MS Word to those requesting it.)
Balanced minerals
A farmer who had two farms a kilometre apart, one peat and one mineral
(clay) soils, gave his calves on the peat soluble mineral mix in the
drinking water, but didn�t think that the calves on the mineral soil needed
any. He phoned me in summer because while his calves on the peat were not
affected by flies, while those on the mineral soil were and were bunching
up. I suggested he give them soluble mineral mix in their water and within a
two weeks they stopped bunching up and the fly problem disappeared.
Heat stress and flies cause cattle to bunch together. This makes them
dirtier which attracts more flies to them. The best way of reducing heat
stress is supplying balanced minerals, both in fertilisers and in soluble
minerals which contain salt and magnesium that help animals control their
body temperature.
When animals are stressed through having an unbalanced diet and/or
insufficient quantity of palatable pasture, heat stress will affect them to
a much greater degree than if getting an adequate balanced diet. These
stressed animals are then molested by flies, which further adds to the heat
stress.
Face flies are attracted to animals which are deficient in cobalt or zinc
because both these deficiencies cause excessive tears from eyes to run down
their cheeks and leave a sticky mess to which flies are attracted and can
spread pink eye.
Controlled grazing
The numbers of flies on well managed controlled grazing farms are far less
than on confinement farms with their heaps of dung. Herman Hempel of
Eldridge, Missouri wrote in the Stockman GrassFarmer that after changing
from confinement to grazing, flies almost disappeared and they had done
nothing to control them.
In the Waikato where there are no confinement cows or beef and only a few
pigs, I�ve noticed a lot more flies on livestock close to towns and believe
that most come from the urban heaps of lawn clippings and poorly made
compost heaps and because there are fewer animals near cities for the larger
number of flies. Also those with animals on lifestyle blocks of a few acres
graze them in very few paddocks so there is no intensive grazing to trample
manure and animals congregate in paddock corners, around troughs and
gateways, creating fly breeding areas. Earthworm numbers are lower because
animal density is lower and liming and fertilising are less.
Controlled grazing can help reduce field bred flies in paddocks and in dung
by reducing long clumps of grass and by trampling dung. Rotational grazing
moves the animals away from flies attracted to their dung. In hot weather,
moving them in the middle of the day leaves many flies behind on the dung
pats, giving the cows a more peaceful time in a fresh paddock.
Move them daily so that they are not forced to lie in their own dung (dirty
animals attract flies and parasites and as they lick themselves they take in
parasite eggs), or made to graze areas where their own dung is breeding more
flies.
Try and plan the grazing rotation so as to move the animals into the
prevailing wind, so that any flies that breed in the animal droppings are
blown away from the animals, rather than towards them.
Earthworms & dung beetles
Earthworms and dung beetles are an important part of fly control by removing
animal manure into soils. Active ones of the right kind in optimum soil and
moisture conditions take dung down so quickly that by the next grazing a few
weeks later it is all removed and animals eat across the dunged area.
The speed of breakdown of dung depends on its consistency (dry takes
longer), whether trampled or not, rainfall, the number of the right
earthworms and dung beetles and the number of other insects. Someone in USA
counted over 400 different species of insects in decomposing dung.
Fertilising with lime, reactive phosphate and correct amounts of natural
minerals rather than superphosphate and other chemical fast release
fertilizers encourages healthy soils, earthworms, beetles and other soil
life. Bird numbers increase when earthworm numbers are high. All reduce fly
and parasite breeding in animal droppings.
There should be at least 20 (40 is better) earthworms per spade spit of 20 x
20 x 20 cm of soil. High earthworm populations eat the animal manure quickly
before flies have time to breed in it and they keep dead vegetation on the
soil surface to a minimum. Earthworm numbers increase rapidly after lime is
applied to soils needing it.
Dung pats should have dozens of beetles - small varieties in wet and cold
climates and large ones in hot dry climates.
Dead vegetation breeds flies, facial eczema spores and causes several
ill-health problems in animals. Toxins in mould of wet vegetaion can cause
severe problems in the rumen and can increase somatic cell counts in milk.
The fungal toxin called Fusarium lowers ewe conception rates. Cows may be
also be affected, although cows are not as sensitive to the toxin as are
ewes. The fungus grows on dead pasture at the base of a mouldy sward,
especially in humid autumns. Some affect animal health and production and
can cause liver damage which can slow animal growth, decrease production and
cause slips or abortions. All moulds and fungi affect animals adversely so
should be avoided, including old toppings (clippings) and mouldy hay or
silage which if fed in paddocks and not eaten breed flies. Earthworms won�t
consume anything mouldy so flies breed in it. Fusarium can produce
Zearalenone on decaying grass which is a fungal toxin that is oestrogenic
and causes a reduction in ovulation and fertilisation rates in ewes
resulting in fewer twins and more empties. It's a major problem for sheep
farmers as it reaches it's peak when the rams go to the ewes in autumn.
Topping increases dead vegetation.
One can smell mould by breaking long grass off at ground level and smelling
the 7 cm yellow base of the plant. Cows normally don�t graze this unless the
40% Grazing Rule is broken.
Where dung is thin as with New Zealand animals grazing lush pasture, dung is
consumed by earthworms and and decomposed much faster than in dry countries
where dung is thick and dry and sits on pastures for months, so is a
possible reason for fewer flies in New Zealand. Dung beetles are plentiful
in game farms remove this dry dung fairly quickly. Are they fewer on ranches
because of sprays?
Caliginosa earthworms are the best because they are more active over a wider
area and move from dung pat to dung pat and change the pat effects from a 30
cm circle to a 60 cm or larger creating lush pasture growth, instead of it
sitting in one place and killing the pasture. Caliginosa earthworms may have
to be bought and placed in pastures. Some earthworms are twice as active as
others. I compared Motueka, South Island earthworm breeder, John Stemmer�s
with our local ones in Hamilton and his were twice as active. When spreading
them on our farm and those of others, green areas developed where they were,
and as they spread across the paddocks at about 20 metres a year. They also
continued to work and multiply longer into the dry periods. It could pay you
to research the commercial and active earthworms available in your area and
do some trials on your farm. See Soils-Earthworms. Because earthworms don�t
travel far they can become inbred. Bringing earthworms from other areas
allows them to cross with yours which gives hybrid vigour.
Beetles may also need bringing in from farms that have them, but they won�t
thrive if the heaps of dung are spread mechanically.
Harrowing
This is called dragging in some countries and rightly so because it is a
drag. Harrowing may be necessary where pastures are dead, root or sod bound
with thatch (dead surface vegetation) and need ripping about to tear the mat
open and spread dry dung. Forget it on good established pastures containing
earthworms and/or dung beetles.
Large dry dung pats may justify spreading. Tyres cut in half around the
circle to give a half round and laid cut face down then tied or bolted
together cost less and spread the manure without damaging the pasture. A
roller can achieve the same.
Until you have earthworm and beetls dung movers, harrowing (dragging) may be
justified, but remember that it spreads dung and larvae over the whole
pasture which then makes it impossible to avoid when grazing so animals eat
less and produce less. If earthworm numbers are low then prior to harvesting
pasture for hay or silage it certainly pays to spread the dung pats,
otherwise they can be picked up and mixed in the hay or silage which lowers
their quality and can infect animals.
Breeding areas
The first thing is to get rid of the fly breeding areas. Flies are attracted
to acid wet organic matter. They need moisture for their eggs to hatch so
look for maggots in organic matter lying around and in moist areas, and try
to eliminate these. Breeding areas include heaps of manure, spilled feed,
soil around concrete where water runoff keeps it wet, calf hutches, silage
stacks and bunkers and water tanks. Flies also breed at the base of long
grass. As well as covered fly traps it is important to have seepage going
into a covered concrete pit and then spread thinly on land for cropping.
Manure and silage seepage spread on pasture can burn it unless diluted.
Animal manure from barns spread too thickly on to fields or pastures also
creates breeding areas. Flies can breed in hay or silage which is fed out on
pastures and not eaten and around feed racks where it becomes boggy and with
the wasted feed create ideal breeding grounds.
A problem that is hard to get rid of is when flies breed on neighbours�
properties.
Reducing fly nuisance
In very hot areas allow them to move to areas where there is a breeze (if
possible) such as under trees to save them bunching up and soiling each
other.
Back and body rubbers containing fly repellants (there are safe ones) or
poisons set near water troughs can help. Change the poisons on a regular
systematic basis worked out with your vet to avoid insect resistance. Work
in with your neighbours on this.
Flies can occur for reasons beyond one�s control so use rubbing posts and
milk-safe sprays that can be used on milking cows. Spray the under part of
their bodies after the clusters are on, to stop it getting onto teats, and
as they walk out, spray the tops of their bodies. It is a pity that some
people, who use insect repellents themselves, don't use them on their
suffering animals. It should be remembered that it is unprofitable and cruel
to expect animals to tolerate flies when they can be controlled. Also use
all the low cost management systems.
Many confinement farmers spray their buildings with pesticides and while
there are ways of reducing flies without chemicals, when flies worry grazing
animals and the suggestions below don�t work it is better to use a chemical
and have relaxed animals than not to spray and have stressed animals.
Life cycles can change from 30 days in cool weather to 9 days in hot weather
causing exponential increases, so be prepared for continuous control.
When necessary treat animals for worms and other parasites.
Effluent
Fresh manure (no older than a week) sprayed onto pastures increases
earthworms and soil bacteria, whereas old effluent can become so
concentrated and toxic that it has killed earthworms unless spread very
thinly in rain, or followed by rain.
Effluent oxidation ponds (lagoons) can also be pumped out to a travelling
irrigator using a pond pump float that floats on effluent ponds. Good pumps
pivot at the mounting to cover a wider area of the pond.
Spreading reactive phosphate and/or agricultural lime over the manure as the
heap builds up speeds decomposition and encourages earthworms and can save
having to turn the compost to get it to break down. If too dry, heaps of
compost can get warm, but should not get too hot because earthworms will
then keep away and soil microbes will not multiply. Adding layers of soil
and keeping it damp without seepage help keep it cool.
Composting with earthworms improves animal and poultry manure, but doesn�t
remove the excess minerals, it concentrates them, but when in a dry form it
doesn�t wash into the soil and kill soil inhabitants like old stored slurry
can.
It is essential to add agricultural lime to it to reduce the smell and
ammonia release which attracts flies. It can be spread under stalled cows
and in gutters behind them. If you don�t believe the benefits of adding lime
do a trial of animal manure in bottles, one with lime mixed in and one
without, with tight lids and smell them after a month, a few months and a
year. You�ll then believe it.
In freezing conditions earthworm activity stops.
There are many species of flies.
Stable flies are costly. If there are flies on your animals, and they are
irritated by them, then you are losing money because of lost animal
production. Where there are stable flies, there are usually house flies
because they breed in similar situations. While house flies may not cost
animal production, they can upset neigbours and your family. Stable flies
have a stinging bite from their probiscis which is used to suck blood for
sustenance. They know to attack the front legs of horses and cattle and the
ears of dogs. They overwinter as slowly developing larvae in wet organic
waste areas below the frost line. When temperatures warm the larvae pupate
and the adults emerge.
Dog�s ears, which stable flies attack, can be protected with appropriate
salves.
House flies are not blood feeders and don�t bite. They are just a tickling
infectious nuisance and live on almost anything moist.
Horn flies are smaller than house flies, breed in fresh manure and live on
pasture, seldom in buildings. They are blood suckers feeding up to 20 times
a day. The number that can cover an animal can suck out 200 grams of blood a
day.
Face flies also spend their time outside except in winter when they�ll seek
protection from cold. They breed in fresh manure and feed on liquid around
eyes, mouths and open wounds. They are the main spreaders of pink eye.
Insecticides may have to be used when stable fly or other fly numbers force
cattle to bunch to try and protect themselves. Sprays can be short-lived if
animals are in long wet vegetation or in water, both of which wash off the
insecticide so avoid them.
Be aware of withholding periods for milking cows and beef slaughter, but
there are milk-safe pesticides.
Use repellents and pesticides to supplement good management, not instead of
it. Be aware that flies can become resistant to insecticides so use them
only as a last resort.
Sheep blowflies are a problem in New Zealand so crutching and dipping or
spraying are necessary.
I�ve seen cattle in some countries so covered with flies that one could
hardly see the colour of the animal. Even parts of Canada with its cold
winters has flies so thick that a car window open in farming areas for a
minute can allow dozens of flies to enter.
A fine water spray over milking cows in the yard helps cool the cows and
discourages flies from worrying them while they are waiting. Well positioned
fine sprays can also reduce the number of flies coming in to the milking
area. Sprinklers should be turned on to cool the concrete before going to
fetch the cows. Once the cows learn the benefit of the sprinklers they will
walk more quickly to get under them, whereas without sprays they dislike
entering the hot concrete yard so slow down just before the yard and have to
be encouraged to enter.
When the summer heat reaches its peak milk production drops, but it is not
always just because of the heat. With heat comes flies, and these can cause
more frustration to cows and owners than the heat. Heat stress and flies
cause cows to bunch together which makes them dirtier still. The best way of
reducing heat stress is supplying balanced minerals, both in fertilisers and
in soluble minerals which contain salt and the other minerals required by
all grazing animals. Salt is the body�s temperature controller, both hot and
cold, so animals also need it in winter to reduce cold stress.
Prevention
There are treated ear tags, cattle rubbers and bags all used as
self-treatment devices for flies such as horn flies and face flies, but
don�t protect cattle from stable flies on the front legs.
The use of biocontrol agents such as parasitic wasps is increasing. They are
small and don't harm people or animals, but they search out fly pupae
because that's where they deposit their eggs. Eggs hatch, the flies are
killed and new wasps emerge to kill more flies. Although they won't
eliminate a fly problem, parasitic wasps will help to reduce fly
populations. The wasps can be purchased from commercial suppliers.
In USA parasitic wasps for the control of flies are sold. Make sure you have
some or watch for adverts for them.
US�sources of parasitic wasp against flies include -
Rutledge Enterprise
4311 Aztec
Pasadena, TX 77504
Tel. (281) 487 0825
Beneficial Insectary
14751 Oak Run Road
Oak Run, CA 96069
Tel. (800) 477 3715
(916) 472 3715
If you use parasitic wasps, release them in the spring and at regular
intervals through summer. By themselves, they are unlikely to control flies
completely. Spraying flies can kill them.
Use all systems and speak with your neigbours about controls. Flies can
travel for many kilometres.
Fly Traps Over Manure
Cover heaps of animal manure completely (100%) with plastic or have fly
traps over them. These can kill thousands of existing and newly hatched
flies.
A frame is made of light timber (lumber) depending on the size of the heap
and has black plastic around the sides down to a metre above the concrete
floor so flies can get to the manure to lay their eggs. The top is also
covered with black plastic, except the top centre which has a turret covered
with clear plastic.
After laying eggs they fly up to the clear plastic top, dehydrate and die.
The maggots help break down the dung and after which they pupate and hatch
and are also trapped and die. The concrete base holding the manure must be
smaller than the frame to avoid flies which hatch from the manure going
sideways and up and escaping. Wind barriers are necessary to prevent flies
from being blown out sideways.
They then die of heat and/or thirst and drop back onto the manure heap.
The trap should be light enough to be lifted off or tilted back for loading
manure in and out.
Composting
Animal manure and vegetation can be reduced in volume by about 50% by using
earthworms and by adding lime to it as the heap is made so that earthworms
consume the manure and turn it into compost or vermicast (compost and
earthworm casts - excreta). If correctly made both will have no smell, are
easy to handle and will be a fertile product which can be spread on pasture,
land to be cropped or sold. Spreading should be done just before rain or in
the case of land, just before chisel ploughing it in.
The lime also encourages soil bacteria to help decompose the manure.
If parts of the compost goes mouldy it will smell which will discourage
earthworms and encourage flies, so apply water. If seepage occurs because of
excessive rain it will smell bad, so cover it during the wet period. The
effluent running out can cause pollution so the manure should be in a
concrete sump.
Birds will be attracted to the earthworms so bird mesh may have to be put
over it.
If pockets of the vegetation go green (like silage) and don't decompose, it
is a sign of the organic matter being spread too thickly without enough
lime. Lime raises the pH and starts decomposition. Earthworms finish it off.
They will multiply and consume the material, mixing it and increasing its
fertilising qualities. Earthworms won�t thrive without lime and it must be
really finely ground to like powder or cement. Trial and error will show how
much lime to use.
Earthworms will not stay in lawn clippings from lawns which have had too
much artificial nitrogen applied, causing high nitrates. I did this once in
our garden compost heap which then got very hot and smelly and and I
couldn�t believe that whereas earthworms had done a great job for years,
they suddenly disappeared and the slimy smelling mess attracted flies. I
took it to the council tip and started again.
In freezing conditions the manure heap will have to be covered with the open
side facing the sun. Correct composting generates warmth which will reduce
freezing when it is not too severe. It should not get hot or the earthworms
will leave. Moisture can help control the temperature.
The only time a fly lands on our compost heap is when it is too dry, too wet
or lacks lime.
Fly Traps for Cattle
An Australian made walk-through fly trap works on the principle of brushing
95% of flies off the animals as cattle walk through. Cattle can be taught to
go through the trap on their way to water or to fresh feed. They also learn
to walk through it for fly relief and for a nice scratch. The brushed off
flies rise to the clear plastic dome which gets hot so they soon dessicate
and die, drop to the ground and are eaten by earthworms and/or ants.
Dairy cows walking through a trap before milking reduces the fly irritation
during milking. If stable flies are a problem make sure that there are
brushes which cover the front legs as cattle walk through. One has world
wide patents and is made by Country Industries, 24 Leonard Crescent,
Brendale, Queensland 4500, Australia. Ph +61-7-881-1609.
Milking Parlors
Many have proved that painting walls a light blue discourages flies. Don�t
make it too light because white attracts flies.
Baited Fly Catchers
Meat baited bottles can catch thousands of flies. They need dark coloured
lids with slots to allow flies to enter. Flies then try and get out through
the light areas, not the dark lid. Heat generated in the bottle soon kills
the flies. These traps can smell so place them where the smell won�t cause a
problem, but close to the source of flies which could be a neighbour.
Spraying
Flies are developing resistance to some chemicals and spraying repeatedly
over several years will only add to the problem. Spray the sites where the
adult flies congregate. Don't spray manure where earthworms breed because
the chemical will also kill them.
Flies & Midges on Humans
I�ve found that wearing white shirts attract flies and midges which then
seem to land on the shirt rather than on the face. As with animals, if you
become stressed and frustrated so start wiping them off your face and
rubbing your face, you will spread their blood and fluids and yours, which
will then encourage more insects to your skin. They are often seeking
moisture. There are insect repellants (some useless and some good ones) that
can be used.
Finally, mono-farming increases all parasite infestations which could be a
reason why game farms with everything from large animals to small birds
don�t have the problems. Free range chickens spread animal manure and
consume flies and their larvae. I�ll bet that the world�s best balanced
farmer, Joel Salatin in Virginia, USA, has no fly problem. He grazes
cattle, rabbits, poultry in natural conditions.
Who said farming was easy?!
Best wishes,
Vaughan Jones
Hamilton
New Zealand
