Higher temperatures brought on by climate change this late spring has brought out all kinds of insects, amongst them the Black Fly, which can cause sickness.

This fly is native to Spain but despite it not being an invasive species, it is still considered a plague as it comes back each year in greater numbers. It’s smaller than a normal housefly measuring between 1.5mm and 5mm.

They don’t sting; they bite which is both painful and in some cases might require medical attention. Like mosquitoes, the female needs the blood of humans and animals in order to gestate. In the case of males (again like mosquitoes) they drink sap from plants.

They need water to lay their eggs so flowing rivers are where they abound, taking to the air in the evening in search of blood.

There have been cases of this best in the UK: The Blandford fly (Simulium posticatum) in England was once a public health problem in the area around Blandford Forum, Dorset, due to its large numbers and the painful lesions caused by its bite. It was eventually controlled by carefully targeted applications of Bacillus thuringiensis israelensis. In 2010, a summer surge of insect bites blamed on the Blandford fly required many who had been bitten to be treated in a hospital.

Bites are shallow and accomplished by first stretching the skin using teeth on the labrum and then abrading it with the maxillae and mandibles, cutting the skin and rupturing its fine capillaries. Feeding is facilitated by a powerful anticoagulant in the flies’ saliva, which also partially numbs the site of the bite, reducing the host’s awareness of being bitten and thereby extending the flies’ feeding time. Biting flies feed during daylight hours only and tend to zero in on areas of thinner skin, such as the nape of the neck or ears and ankles.

(News: Andalucia)