Towns in Spain are being invaded by flies: Is climate change to blame?

Towns in Spain are being invaded by flies: Is climate change to blame?

In parts of Spain, flies are making life hell for residents.

Tomiño, a municipality in the province of Pontevedra in the autonomous community of Galicia, has had a sudden influx of common flies. The moment they hatch, they go looking for food and are often attracted to smells from people’s homes.

Mayor Sandra González told local news that, while the insects don’t spread disease, they are “deteriorating the psychological health” of the people suffering from the outbreak of pests.

She says the situation requires a coordinated response from authorities in the area to tackle the causes behind the invasion of common flies.

A report from the Galician Federation of Municipalities and Provinces on behalf of town councils in Galicia states that up to 20 areas across Pontevedra, Lugo, A Coruña and Ourense are suffering from an explosion in fly numbers.

Some mayors of towns on this list, however, have denied there is a problem in their area leading to claims that the scale of the issue is being overblown.

What is causing swarms of flies in Galicia?

Though there is currently no way to connect swarms of flies in different municipalities, experts have a few theories.

A study carried out in the municipality of Tomiño by a research group from the University of Vigo suggests that climate change and poor agricultural practices could be two factors driving the increase in fly numbers.

Heavy rain has been followed by hot weather and humidity is high. Combined with organic matter like fertiliser rotting in fields, the perfect environment is created for flies to lay eggs, and their larvae to hatch and rapidly grow.

While there have always been farms in Tomiño local residents told newspaper El Pais that the fields are now being fertilised more frequently to increase food production. They say fertilisers are being sprayed directly onto the soil where they remain for weeks, providing a breeding ground for flies.

Flies also go dormant in the winter when temperatures drop below zero degrees. But unusually warm winters have meant they are reproducing throughout much of the year.

Storms slow down their proliferation, discouraging swarms of flies, but soon this combination of climate and agricultural conditions returns and with it these insects.

Scientists say that, while there has been a disproportionate boom in the number of flies, this can’t be called a plague. In municipalities like Tomiño, however, insects have been found in some cases in “absolutely intolerable densities”.

They believe that if more towns complain, further research is also needed across the region to get a better picture of the situation across different regions - some of which are hundreds of kilometres away.

What can be done about the fly problem?

Twenty town councils have come together to demand coordinated action from the regional government on the issue. They want community collaboration to reduce the perfect storm of conditions that can lead to extreme numbers.

Experts say guidelines on cleaning up agricultural practices to prevent their proliferation could be helpful - something that the regional government could provide guidelines on.

Some towns are also studying ways to increase populations of birds and bats that eat the insects in an effort to keep numbers down in badly affected areas.