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Parasites Control Flies Naturally

By Holly Martin

It is an age old problem - flies. Anywhere there are confined livestock, there are flies.  It starts in early spring, just when the rest of the world is greening up and temperatures are warming up.  No one really thinks about it, until they are everywhere--- annoying livestock and the people that handle them.

For years, in confined livestock operations, producers have been searching for an economical, safe and convenient way to control their fly problem.  And the solution, some producers say, comes in the form of another insect.

The beneficial insects, tiny wasps, interrupt the life cycle of the fly, says Dr. Robin Betschart, a Torrington, WY, veterinarian.

"These wasps control filth-breeding flies, which include house flies, stable flies, face flies and horn flies," she says.  The wasp species is about the size of a gnat and does not sting animals or humans.

The filth-breeding flies like to lay their eggs in manure and decaying vegetation, which makes dairies and feedlots an ideal place for mass reproduction.

Betschart uses the parasites around her veterinarian facilities, Borderline Veterinarian Clinic and Equine Center.  Betschart also raises horses and says that horse manure is prime breeding ground for flies. "The manure contains a high level of decaying vegetation."

She was first introduced to the beneficial insects while doing veterinary work for feedlots.

Kunafin, a company that distributes a number of beneficial insects, worked with the feedlot, and Betschart now distributes their product.

Betschart began using the parasites around her facilities because horses can be sensitive to chemicals.  She likes using biological control close to her home.

The concentration of manure and silage, at dairies and feedlots, are the breeding grounds for flies.  The larvae transforms into fly pupae.

As the parasitic wasps are released into the environment, they search out the fly pupae and lay their eggs inside the pupae. The wasp larvae consume the fly pupae.  The wasps then emerge from the pupae as adult wasps and the cycle starts over.

Kunafin ships the parasites, from their insectaries, in the pupae stage, while they are still inside the fly pupae.

By the time they are distributed, the adult wasps are ready to emerge, breed and lay their eggs.

"You need to put them out once a week during fly season," Betschart says.  The frequency of the distribution is tied to the life cycles of the flies and wasps.

"The fly life cycle is 14 days and the wasp is 21 days," she says.  Since the flies can reproduce faster than the wasps, they will get ahead if producers don't continue to put out the parasites.

The short life cycle also is why the fly problem seems to get continually worse during the summer.

The control ideally should start with the first sign of flies during the spring.  This prevents them from getting large populations before trying to control them.  "It is a foot race," Betschart says. "And you want the wasps to get ahead."

Parasites then should be distributed weekly, until the first killing frost.

Betschart says that distribution of the pupae is relatively simple.  Kunafin ships the pupae in bags directly to the producer. Betschart says she pours them into a five gallon bucket and scatters them any place the flies breed.  Ideal breeding grounds are undisturbed places, such as at the base of bunks, hay stacks and silage pits.

"The more uniformly you spread them, the better they work," Betschart says.

Betschart says it is possible for an operation to get to the point that continually distributing the wasps isn't necessary.  But, she says, if there are several livestock operations nearby, the need always will be there.

"In some areas, where there are several dairies that have all been using the beneficial insects for 10 to 15 years, it is basically a fly-free environment," she says.

For most people, the number of beneficial insects that are needed remains the same, or drops some after the initial control is achieved.  "In isolated areas, where they use these
wasps diligently and do it correctly," she says, "they will be able to decrease their numbers."

Different operations will need different amounts, Betschart says.  The numbers depend on the number of animals in the facility and their management practices.

Betschart says she sees two major benefits to using natural control of flies.  "Chemicals that target flies also killed other beneficial species," she says.  Chemicals that can kill insets are catalysts for the beneficial breakdown manure and vegetation. "Feedlots that have used chemicals for years can be manure monsters," she says.  The
manure doesn't breakdown as easily when those insects are controlled, Betschart says.  In addition, the manure is not as useful as a fertilizer, because the nutrients haven't been broken down.

The second major advantage beneficial insects have over chemicals is effectiveness. "Every year you use chemicals, they become less and less effective," she says.  Insects
become immune to the chemicals. Producers are forced to keep changing products to control their fly population.  Flies do not become tolerant to their natural predators.

Environmental concerns also make the biological control important.  "That is nature's way of fly control," Betschart says. "We aren't importing something that isn't part of nature."

With the public's increasing concern for the environment, using a natural control method makes sense.  "Environment issues are at the forefront," Betschart says.  "Cattlemen are concerned about the land.  They are about it and their cattle."

With more government a regulations on chemicals, there are fewer effective controls available. If cattle producers can use an environmentally sound practice and achieve the same results for a better price, they will be interested, Betschart says, "This is the leading environmental friendly method of fly control."

The biggest benefit most producers see is the cost of using biological fly control.  "For the same level of fly control, it is half the cost of chemical," Betschart says.

Ken Betschart, manager of Torrington Feeders, agrees that cost is a big benefit.  "You get better control for less money," he says.

Betschart has been using the parasitic wasps for nine yeas, at several feedlots, from Oklahoma to Wyoming.  Since he has been using biological control for many years, he isn't sure exactly what the savings are over the current chemical treatment.  when he first looked into it, a cost comparison was run and he found the feedyard could cut their fly
control costs in half, at a minimum.

The hassle of handling pesticides also makes the biological control an ideal choice, Betschart says.  There is no messing with regulations or licensing of applicators.  Distribution of the parasites around the 26,000 head feedlot takes about 30 minutes, he says, "no more than it takes to drive around and spray the yard."

When Betschart came to Torrington five years ago, flies were a problem.  Perimeter bunching becomes a problem when the cattle are bothered by the flies. "The flies go to the shade during the hot part of the day," he says. When it cools down, the flies come out.  They push the cattle back, away from the edge of the pens and the bunks, cutting feed intake.

Torrington Feeders began using the parasitic wasps and since then "there are virtually no flies."

To supplement the biological control, the feedlot also maintains the pens to keep fly breeding grounds to a minimum. "If you take their roosting and nesting areas away, then there will be naturally less flies," Betschart says.  Sugar bait also is used around the buildings, especially during the fall, when flies are looking for the warmth of buildings.  Chemicals are used around the horse barns or the species of flies that the parasites don’t control.

"To me, it is alot more cost effective and alot safer, because we don't have to mess with chemicals," she says.

If producers do decided to use the biological control, Robin Betschart says, they need to make it a commitment to it.

If the parasites aren't routinely distributed, they won't work.  Producers shouldn't put out the parasites and then decide to spray, too, she says.  Any chemicals used to kill flies, also kill the beneficial wasps.  They can do some supplemental control measures, such as sugar baiting and some premise spraying, which helps control the flies even further.

Even though the parasites are most effective for confined operations, Betschart says anywhere there are flies the parasites can be used.

"Ranchers can use them as one more tool in controlling flies," she says.  The parasitic wasps can be spread around areas that cattle congregate, where there is a higher concentration of manure.  Areas around the water tanks, salt licks and corrals would be ideal.  "It won't eliminate the flies, but it sure will cut down the number," she says.

The insects work well also for home gardeners, who have compost piles where flies like to breed.

"They work for anybody, from the feedlot to the backyard gardener," Betschart says.





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