The main nuisance flies in Zimbabwe are the common house fly (Musca domestica) and the stable fly (Stomoxys calcitrans).These constitute a major source of economic loss to livestock breeders for two reasons:
1. They cause loss of production in terms of milk and meat because of the stress placed on animals under attack and
2. More importantly, they transmit disease from infected to sick animals e.g. opthalmia, mastitis, parafilariasis.
Any fly control program must take place early in the breeding season i.e. as the weather starts to warm up, after the first shower and before the first major rains. If started too late, the fly population will be so high that it may be impossible to control it. To be successful, a fly control program must target all stages of the fly life cycle at the same time and must rely on management and biological methods as well as insecticides.
Flies lay their eggs on rotting vegetable matter, manure, refuse etc. They need a damp, (but not too wet) and warm environment. The first control method is to remove potential breeding sites. Animal housing such as calf pens, poultry houses, piggeries, stables etc should be kept clean and hygienic. Particular attention should be paid to areas such as drains. Manure must be collected and treated in one of several ways. Composting the manure in heaps causes the manure to heat up to such an extent that the eggs and maggots cannot survive. The surface of the compost will have to be covered or treated with a product such as Neproex 50. Drying the manure removes the moisture necessary for development of the maggot and is also a friendly environment for predators of the eggs and maggots. A third option is to wet the manure excessively e.g. dairy slurry pits, where the environment is too wet to allow successful breeding by the flies.
Flies rest on buildings, walls, ceilings and these areas should be sprayed to run off with a recognised insecticide, such as Agita 10WG, following the manufacturer’s instructions.
The third area to attack flies is on the animals while they are feeding. Synthetic pyrethroids such as Deltatick Pouron, Ektoban, Paracide, Pouricide NF and Sentinel 15 will kill flies landing on the animal.
There are also many types of fly traps on the market, or it is possible to make them oneself. However, fly traps on their own, without any of the abovementioned control methods will have little chance of controlling the fly population.