How to get rid of cow flies once and for all

Black Angus cattle being bothered by flies and mosquitoes.

Dear Daktari,

I am a farmer based in Kericho County. I have four dairy cows and a few pigs. One of the major problems I am unable to deal with over the years is flies. They are such a nuisance even to the animals and I am not sure if this is the right observation or something in my mind but I have noticed when I have someone chasing away the flies, there is a slight increase in milk production. I am not sure whether these flies can spread diseases but I don’t like the disturbance they cause to my livestock. How can I deal with this problem?

Mr Ng’eno, Kericho County

Thank you Mr Ng’eno for reading and most importantly for finding time to share with us your problem.

Farm flies are a nuisance to animals and they come in many types – stable fly, horn flies, face flies and biting flies among others. They not only bite animals but can also bite people on the farm.

Normally these flies feed on blood and some in the process spread diseases from one animal to another. Other flies for example tsetse flies spread the fatal nagana disease in animals and sleeping sickness in human beings. Face fly spread pinkeye disease in cows.

As Ng’eno rightfully puts it, these flies normally capitalise on restrained animals for example during milking when they can also maximally suck blood easily.

It is true that their presence at milking can have negative effect on milk let down. This flies will bite the face, legs, back, belly or ears of animals. The result is normally stumping, kicking, clustering together and tail switchingas a result they reduce the feeding time and hence the amount of feed intake subsequently reducing the growth rate and productivity.

Below are some strategies that a farmer can employ to reduce the population of such flies on the farm and therefore minimise disturbance to the animals.

Locate the source of flies?

Most farmers don’t have good waste management systems on their farms. The problem is especially worse in pig farming and this normally creates favourable conditions that attract flies. Manure piles, compost pits form good breeding grounds and home bases for flies as they provide the warmth, moisture and food for the larvae; farmers may still benefit symbiotically from this as they aid in decomposing. Locating such pits away from the animal houses can help in diverting their attention on animals. Use of vertical piles with a crust at the top makes manure unfavourable for flies and reduces their population. Spreading the manure waste in thin layers also makes it unfavourable to flies.

Keep the house clean and dry

Flies have a liking for dirty and wet environments. When the milking parlour or pig sty are dirty and wet, it will attract flies which will end up biting the animals. Keeping the animal unit clean keeps away the flies.

Fly traps

There are several types of fly traps in the market, some work through colour attractants and others through odours. Others have sticky surfaces that trap insects that land on them – this have been used in tsetse fly control. The traps can be hanged inside the dairy unit or near fly breeding grounds. When using such traps, carefully read the manufacturer’s directions on how to use.

Netting

Netting of zero grazing units doesn’t only serve as a physical barrier but also kills the insects. The nets are normally treated with insecticides that kill by contact. The use of these nets on cattle units also by extension reduces cases of malaria by killing mosquitoes. The nets are currently marketed as Zero Fly Nets and are available in agrovets.

Chemical Control

Chemical control involves use of larvicides in animal feeds or on composite pits or use of insecticides sprayed on animals.  Pour-On have long lasting effects once applied on the backline of the animal. The insecticides when sprayed on animals kill by contact. Care should be taken when using chemical control to avoid contamination of feeds and milk.

Fly Predators

Beetles, mites and wasps feed on flies and have been shown to be an effective biological control of flies. The predators feed on fly larvae thus reducing their populations.

(Dr. Othieno was the Vet of the Year 2016 and works with the Kenya Tsetse and Trypanosomiasis Eradication Council – KENTTEC, [email protected])