Find non-chemical alternatives to control flies and red mites

A growing number of egg producers are turning to parasitic wasps and predatory mites to control the populations of flies and red mites.

Keeping flies and red mites under control is an ongoing struggle for egg producers, especially when the weather warms up.

During the summer months, the red mite life cycle speeds up to just 7-8 days, making them harder to control, especially since they only appear at night.

This means that the first sign of infestation is often anemic birds or blood-stained eggs.

Red mites can take a significant toll on a flock by causing restlessness and lack of sleep in birds, and by being carriers of disease.

They are also an economic burden for farmers as the mites can cause a decline in egg production and quality, resulting in annual economic costs of up to £ 1 per hen.

Manufacturers have long relied on acaracide chemical products to keep control in their barn.

However, many products have been withdrawn from the market due to consumer safety standards and those that are still available suffer from ever increasing resistance to red mites.

This has led to the increasing attention paid to treatments on a non-chemical basis.

Predatory mites

APPI Biotech is part of the Koppert Group, the world leader in biological pest control for horticulture.

For ranchers, they produce a range of natural solutions based on beneficial insects that protect their animals from pests.

They commercially breed two types of predatory mite, androlis and bull, which are released into the home to control and prevent red mite infestation.

Jeroen Koppert, Founder and Director of APPI, said: “Both species of predatory mite are native to the UK and are commonly found in wild bird nests.

Completely harmless to birds, humans and the environment, they can reach the inaccessible hiding spots that chemicals and humans may overlook.

“Unlike chemicals, there is no chance of resistance, which greatly improves the health of your birds.”

The androlis and bull mites work together very effectively by targeting different stages of the red mite cycle.

Androlis feed mainly on red mites, which are in their juvenile stage and are a very mobile predator, while the bull is more voracious and prey at all stages, but spreads more slowly.

Jeroen explained that using predatory mites is quite simple: “There are several methods that can be used.

“Depending on the order, you will receive buckets from Androlis and Stier in different stages of life that you can sprinkle on the floor, nesting boxes and slatted frames.

“You can also get large bottles of the predatory mites that are held in place for slow release”.

He continued: “The predatory mites will then find the red mite and eat it. Predatory mite populations will grow as they feed on the red mite, but when the red mite numbers are low, their numbers will also decrease because there is not enough prey to feed them.

“As the red mite populations increased again in the warmer months, more predatory mites need to be added to maintain the red mite population.

“Year after year, red mite populations are becoming easier to control.”


ADAS researchers are currently working as project partners in the MiteControl project, which is investigating novel methods of combating red mites in commercial laying systems.

ADAS’s Jon Walton said they were testing predatory mites in the process.

“We now have three farms in the UK that are testing both Androlis and Taurus species along with a water additive as part of an integrated pest management (IPM) trial.

“The principle of an IPM approach is to use a combination of non-chemical methods to keep the red mite population at acceptable levels,” he said.

Jon explained that they could see the effects of the predatory mites while the experiments were still going on.

“One of the farms has just been depopulated and has shown positive results,” he added.

“We had a control point where we used a chemical to control the red mite, while in the test house we only used predatory mites and the water additive.

“The experiment started in May last year when we saw some very warm temperatures and we measured the number of red mites with traps in both houses.

“We saw an initial high in the number of red mites in the test house, which was much higher than in the control house.

“However, the numbers slowly went down, and in the end we found that we had better control with the predatory mites in the test house.”

Jon continued, “Predator mites are not necessarily going to have an immediate effect, it will take a while to establish themselves.

“As with any predator-prey relationship, there will be an increase in the prey population followed by an increase in the predator population.”

Fly control

Flies can be another big problem for egg producers in the summer months as they irritate chickens and spread disease, which means it is important to act early.

Since chemical controls are both expensive and an environmental risk, APPI offers an alternative – parasitic wasps.

The parasitic mini wasps are a natural predator of the fly and differ morphologically from the typical wasps you can imagine, as they are hardly larger than a pin head and inconspicuous to animals and humans.

Jeroen Koppert explains how they work: “The mini wasps are introduced every 14 days or monthly into areas where flies like to breed – typically near dirt, feeding areas and watering areas.

Since chemicals are expensive and an environmental risk, there is an alternative – parasitic wasps

They work by injecting their own eggs into pest fly pupae, which then feed by consuming the contents and hatching into new mini wasps rather than pest flies.

He also said it was important to get a handle on a fly population before it becomes a problem.

“We generally recommend starting a fly control program early in the season, usually in early to mid-spring, so that a population of mini wasps can be established to control the juvenile stages of pest flies before adults become a problem.”

APPI currently has customers using the mini wasps in both organic and non-organic locations.

“We generally do not recommend using chemicals in conjunction with the mini wasps, and care should be taken to avoid placing them in an environment that contains residues of chemicals from previous treatments.

“Of course, resistance is not possible with our biological methods because the mechanism is physical and not chemical,” he said.

On the farm

Nick McTurk operates a flat deck system of 16,000 birds in Essex and uses both predatory mites and parasitic wasps from APPI.

“We have been involved with eggs for 12 years now and began our control of flies and red mites with conventional chemical-based products,” he said.

“We had pretty good control but had to take a lot of precautions to avoid residue and I found it very difficult to avoid the chemicals when applying with a backpack sprayer.”

This meant Nick was looking for an alternative solution, and when he came across APPI’s biological pest control solutions at the Pig and Poultry Show, he thought they were worth trying.

Nick initially decided to test the predatory mites: “We initially only used the predatory mites in one house and had the same level of control as in the other houses where we continued to use chemical products.

“Since then we have done all of our red mite control with predatory mites and find that there is a cumulative effect on the herds, with control improving year on year,” he said.

“With conventional chemical control you always work on the back of your feet and when the population gets too big you attack them, while with biological control it’s easier to get control of the population before it gets too big.”

Nick explained how his control normally works over the course of a herd: “If we had started a flock in December in a normal year, we would drop our first dose of mites in April or May when the weather warms up.

“Then we gave another dose about every six weeks until we reduced the applications in the fall.

“This year we had to do a few more applications because the temperature in the stalls remained relatively high because the birds were housed.”

More recently, Nick has been using the parasitic mini wasps to control flies: “We give one dose at the same time as the mites in spring and then another dose in summer.

“We got on very well with it and have had absolutely no problems with flies since the start of the mission.”

He added, “They arrive in little tubes, about eight inches long, full of sawdust and dolls that I just sprinkle as evenly as possible over the slatted surface while I also spread two tubes on the dung heap.”

“I’ve now almost completely eliminated chemicals from my stalls, which means I don’t have any residue or other challenges associated with storing and using chemicals while maintaining a good level of control over the fly populations.”

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