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The episode of extreme heat that hits Spain advances the arrival of the black fly

2022-05-21T22:34:18.178Z


The high temperatures and the absence of rain accelerate the reproduction process of this mosquito and its presence in the territory.


Spain faces the first episode of extreme heat of the season, with a weekend that will reach temperatures well above the seasonal average.

However, having to deal with 40° in the spring is not the only risk to public health at this time.

The grades rise and the black fly also returns, the fearsome insect that multiplies without control in the river flows.

Rising temperatures are your greatest ally.

The heat not only speeds up their metamorphosis process —that is, they go from the larval stage to the adult in less time—, but also extends the reproductive window and, therefore, their presence in the territory.

The heavy rains in April partially mitigated their presence, but this episode of extreme heat will put an end to this truce.

It does not measure more than six millimeters, it is black and has white wings.

Despite its name, it is not a fly, but a mosquito whose painful bites in some cases result in an emergency visit.

When these flies close their jaws, they inoculate saliva with anesthetic substances that initially prevent pain, but which can immediately cause strong allergic reactions in the most sensitive people.

In Africa, Venezuela and Brazil, the black fly even causes the transmission of some infectious diseases, such as onchocerciasis (known as river blindness).

Jorge Galván, director of the National Association of Environmental Health Companies (Anecpla), a national leader in pest control, warns about the possible threat in Spain.

“For now we don't have the vectorial problem in Europe.

But climate change represents a risk factor for tropical diseases to reach our territory”, points out the expert.

Contrary to popular belief, the black fly (

Simulium erytrocephalum

) is not an exotic insect that has colonized Spain.

It is actually an autochthonous species present throughout the national territory, although in Andalusia, Aragon, Catalonia, Madrid, Murcia, La Rioja and Valencia it represents a real problem during the summer.

The rivers of these communities -the Henares, the Manzanares, the Jarama, the Tagus, the Anoia and the Ebro, among others- have the perfect conditions for this insect to proliferate.

Óscar Soriano, a scientist at the Higher Council for Scientific Research (CSIC) and director of the Insect Surveillance System in Madrid, sums up the problem like this: "The better our rivers are, the worse the black fly is."

Its waters are clean enough for aquatic plants (macrophytes) to grow where the black fly lays its eggs,

Prevention and control

The black fly plague has a solution and it is very easy to control, according to the experience of Javier Lucientes, a prion and vector disease researcher at the University of Zaragoza.

“We have all the technologies and products to put an end to it.

I wish all mosquitoes were so easy to keep an eye on,” he says.

Given the difficulty of achieving an optimal level of water cleanliness so that the problem can be resolved naturally, today the elimination of the larvae is the most effective treatment against this insect.

Placement of a mosquito and black fly trap in Barcelona.

BARCELONA COUNTY COUNCIL (Europa Press)

The most widely used product is a bacterium, harmless to the rest of the fauna, which kills the larvae and cuts the aquatic plants where the adult lays its eggs.

However, to work it is necessary that all communities act aggressively at the same time, without leaving a single stretch of river uncleaned, since the fly can fly up to 20 kilometers.

This condition is never met, denounces Lucientes.

Madrid and Aragón, the communities most affected in recent years, do not have a centralized plan to eliminate the black fly.

It is up to the City Councils to take charge of the problem and, faced with failure, each one leaves the ball on the neighbor's roof.

The cleaning of the Manzanares River began only on Wednesday in the Madrid capital -responsible for the treatment of 30 kilometers of river-, while in Getafe (10 kilometers) they have already carried out 18 of the 90 total prospections planned and six larvicide treatments.

The winter and spring of heavy rains have allowed the campaign to be delayed in Zaragoza, one of the towns with the highest incidence of black fly at European level.

The disinfection work on the banks of the Ebro will begin at the beginning of June, in time to control the bite peak expected for the month of July.

"That's when we'll see the fruits of this weekend's heat wave," explains Lucientes.

How to protect yourself from the black fly?

Contrary to the rest of the mosquitoes, the black fly is a diurnal insect that bites at any time of the day between May and October, although they are more active at dawn and dusk.

It lays its eggs in the vegetation of rivers, therefore it is advisable not to carry out activities near watercourses such as reservoirs, wetlands, gardens with fountains and rivers.

It is also better to wear light clothing - dark colors and patterns attract her - that covers arms and legs, which are the parts most exposed to her bite, or use a repellent. 

Its bites are recognized by a red dot that it leaves on the skin and by the inflammation that can last up to a week.

In some cases, it can cause dermatitis, edema and itching.

Experts advise against scratching, to prevent the wound from starting to bleed.

To relieve the pain, ice or a corticosteroid ointment can be applied. 

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Source: elparis

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