It's not just your perception: Why mosquito season lasts longer than it did years ago

Until a few years ago, mosquitoes were basically a nuisance closely linked to summer. But recently, that reality has been changing. Although it's difficult to establish strict rules regarding these mosquitoes, there are more than 60 species in Spain alone.

And although to most mortals they all seem very similar, each of these species differs greatly from the others, as explained by Roger Eritja, entomologist and head of the Entomology and Data Validation area of Mosquito Alert, at theCenter for Advanced Studies of Blanes , a research institute of the Spanish National Research Council (CSIC).

"Each species lives in different environments (urban or rural, for example) and has different habits. Their density at each location depends on the availability of water for breeding and their ability to disperse." Furthermore, there are diurnal and nocturnal "habits ."

Added to all this diversity is the fact that, according to the expert, "there are about five invasive species in Europe, three of which are in Spain. Their worldwide spread is related to globalization." In other words, we humans ourselves bring them from other places, primarily through the transport of goods .

It has to do with climate change

Some of the changes we're experiencing (some of them right here on our own) are related to climate change. The most obvious is that "the life cycle of mosquitoes may be accelerated, which means more mosquito generations per year ," says Eritja.

But what's more, and this is one of the most significant changes, is that they're present for longer : as the warmer weather starts earlier, their activity begins earlier, in spring. Similarly, because the heat wave lasts longer, mosquitoes remain with us longer. They're even present during the increasingly mild winters.

The climate emergency is not ideal for mosquitoes: if temperatures rise too high, the heat will kill them.

The other consequence of climate change is that it can "make mosquito invasions possible in colder climates, probably more so in mountain environments ," according to the Mosquito Alert entomologist.

The fact that this spring has been particularly rainy doesn't necessarily mean that summer will have more mosquitoes than usual because, as the expert assures, "mosquitoes have a short lifespan, no more than 15 days. So the spring rains will have increased the number of mosquitoes in spring."

On the other hand, the appearance of the first heat wave in June, earlier than usual, doesn't necessarily mean there will be more mosquitoes this season, because "the climate emergency isn't ideal for mosquitoes either: if temperatures rise too high, the heat will kill them. If there are prolonged droughts, mosquitoes won't be able to reproduce, and theoretically there will be fewer of them," he concludes.

Communicable diseases

Experts' greatest concern regarding mosquitoes relates to the diseases they can transmit. In the local area, Eritja specifically highlights the West Nile virus, which is transmitted by mosquitoes from infected birds.

Regarding imported diseases, "the tiger mosquito can transmit exotic diseases such as dengue, Zika, or chikungunya . But for this to happen, there must be already infected people within its range. This is difficult because these diseases are not present in our country. In other words, a sick person, infected in remote countries, must arrive in Spain to initiate local transmission through a tiger mosquito."