Goat Farms

As we approach summer, its easy to forget how much of a nuisance flies can be, but before we know it they will be back irritating you and your animals! Prevention is better than cure and it pays to tackle the problem biologically.


Within Kwaligeit, the Dutch Goat Milk Supplier’s quality control system, every goat farmer is obliged to prevent nuisance from flies in the milking parlour and the tank room. A large amount of flies is a nuisance for both humans and animals and the stress created by a fly infestation will deplete a goat’s energy, at the expense of milk production. Furthermore, flies can play a role in the spread of health problems such as salmonella and mastitis. With biological control, flies can be safely and effectively tackled before they get to the nuisance stage!

We all know there are several chemical pesticides against flies, but flies often build up resistance to the active ingredient and as such they are not a long term solution. There are also many products to catch flies, such as fly lamps and sticky tapes. The big disadvantage of these products is that they only work if the fly is already a fly- they do not address the juvenile stages of the fly; that of egg, larva and pupa. The entire fly life cycle consists of eggs, then the larvae and then pupae. In a fly infestation, the adult flies you see are just the tip of the iceberg. Biological fly control fights flies at every stage of the cycle. 

APPI’s technical consultants will assist you throughout your fly control programme, from providing a tailored programme to advising on a specific protocol for your site. Furthermore they guarantee the quality of the living product “Protocols can also vary considerably, and that can affect the degree of effectiveness,” said Guido Hakvoort of Rentokil Agro Pest Control, one of the Dutch distributors that works with Appi’s biological products.

Hakvoort and his colleague Arno Bakkers see biological fly control as the future. “In the future, you will only be allowed to use chemical agents in extreme situations. So you’d better be proactive.” There is another important argument for choosing biological control, says Hakvoort. “Goat manure is a popular fertilizer product, but you don’t want the possible after-effects of chemical agents in it. If you fight flies biologically, you prevent chemicals in the manure and on land”.

The biological approach uses natural enemies for each life stage of the fly. Predatory mites eat the eggs and youngest larvae of flies. (Female) parasitic wasps lay eggs in fly pupae after hatching, and when these eggs hatch, the larvae of the parasitic wasp feed on the contents of the pupa – this interrupts the life cycle thereby lessening the adult fly population. Hakvoort advises using both predatory mites and parasitic wasps. “We work with a protocol that addresses all stages of life of unwanted flies. The predatory mite and the parasitic wasp reinforce each other; all the eggs that the predatory mite has eaten no longer have to be parasitized by the wasp at a later stage.” A parasitic wasp is the size of a pinhead, a predatory mite the size of a pin point – so you don’t see them. These beneficial insects are 100 percent safe for humans, animals and the environment, APPI assures. In addition, they always stay close to the point where they are released, because the miniwasps are not very mobile and of course also because they find their food there.  The complete protocol also includes a flytrap that lures flies with a bait based on natural components. “This catches stray flies  around outside the buildings, thereby preventing them staying to lay new eggs.” the biggest effect you have is if you follow the entire protocol. “But it also has to be paid for, so not every goat farmer chooses all parts of the protocol, or applies it to all stables. That’s why we create a tailor-made protocol for every company.”

According to Hakvoort “Biological fly control ideally starts early, usually in Spring, and continues until about the end of November”. Joenie van der Vliet of APPI in the Netherlands says: “Because in goat barns the conditions such as climate and humidity are good for flies to develop, we advise to start as early as possible in the season. Then a population of natural enemies can be built up that can immediately control the development of unwanted flies.” The predatory mites are supplied in tubes with a kind of potting soil, the wasps have a wood shavings substrate. Hakvoort: “The majority of parasitic wasps are still within the parasitized fly pupae on delivery and are yet to hatch; the warmer it is, the faster they come out.” These natural enemies are best released where flies like to breed; along the sides of the feeding troughs. “A fly doesn’t deposit its eggs where the goats stand and lay,” Hakvoort said. How many tubes need to be sprinkled depends on the size of the shed. According to the protocol, you get new tubes every four weeks and thus replenish the amount of mites and wasps. “A parasitic wasp only turns three weeks old and cannot reproduce sufficiently, so scattering is necessary,” Hakvoort explains. Van der Vliet adds: “It’s all about the natural balance. In an oversized population with stable and house flies, by introducing predatory mites and parasitic wasps, you ensure that a natural balance is created, which reduces the nuisance flies. The unwanted flies continue to develop. By carrying out further releases of natural enemies, you ensure that the populations remain balanced.” Hakvoort discusses mucking out: “When you muck out, you start with the mites and wasps again in a zero situation, so it is wise to do another release again a week later. It takes some planning.” A few years ago, Hakvoort recalls, the fly season lasted about nine four-week periods. “But with mechanically ventilated stables it is always warm, making about eleven periods of four weeks. So that’s almost the whole year around.” The moment the natural enemies are in the barn, you will not immediately see results. Hakvoort: “But throughout the season you notice that the fly nuisance is low. It’s not like you don’t see a fly at all. But if you see 70 percent reduction, it’s neat, and then you really do notice a difference”.

Do it yourself

Biological fly control in this way is easy for the farmer to apply themselves. They are natural solutions so anyone with knowledge of the site is able to apply them, no additional PPE or qualification is needed. 


Christian and Monique van Summeren keep 3500 dairy goats at their home location in Stramproy and put in 20-30 tubes every six weeks. They have fought flies biologically from when they first kept goats. “It appeals to us that you don’t have to use pesticides. You create a balance that is very beneficial in terms of work. You scatter the natural enemies and they do the work. Nor does it have any adverse effects on the environment.” The Van Summerens like the biological control. “It meets our expectation.”

Christian and Monique van Summeren