The black fly is not an invasive species in Spain but in recent years the numbers have grown, especially in areas close to rivers, and the National Association of Environmental Health Companies (Anecpla) is warning that it is known to have caused serious illnesses in other countries, especially in Africa, Brazil and Venezuela.
So far the black fly has not caused any health problems in Spain, but Anecpla says the effects of climate change mean that it might. The only way to prevent this, the association says, is to increase prevention and control. “The administrations must make major efforts to control this species, because otherwise it could result in an important public health problem in Spain,” says Sergio Monge, the president of Anecpla.
The black fly is a transmitter of serious infectious diseases such as onchocerciasis, which is endemic to several countries in sub-Saharan Africa, Brazil and Venezuela, where according to the World Health Organisation around 18 million people have been infected and some 270,000 have been blinded by this disease. It is also known as 'river blindness', because black flies breed near rivers, especially ones where the water is clean and there is floating vegetation.
The regions of Spain most affected by the presence of black flies are Andalucía, Aragón, Catalonia, Madrid, Murcia and Valencia, where the insects have grown longer than ever before (about 6mm) mainly due to the rise in temperatures in recent years.
Black flies do not sting, but they bite, causing quite a large wound which is very painful. If it becomes infected, or someone has an allergic reaction, they could end up in hospital. Experts say that anyone is bitten by a black fly, it is important not to scratch the wound, because it will get worse and could become infected. They recommend applying ice to reduce inflammation, or a mild corticosteroid ointment, but say it is best to go to the nearest health centre or hospital to prevent the reaction getting any worse.
Unlike other flying insects, black flies are active during the day and can get under clothes and reach the skin. To avoid them, ANECPLA suggests wearing pale-coloured clothes and not bright colours as these could attract them; avoid areas near rivers, especially late in the afternoon; fit mosquito netting to doors and windows in areas which could be at risk; prevent water accumulating outside the home and keep water containers covered; control drainage; and use certified repellents, especially those that contain citronella.