Every year the Barcelona Public Health Agency (ASPB) identifies public spaces in the city where certain elements pose a risk of mosquitos proliferating, the main goal being to eliminate breeding spots and prevent their reproducing. This year, the Pest Control and Monitoring Service has selected 82 hotspots where mosquitos could proliferate, and where prevention and control measures will be taken.

Monitoring and prevention are stepped up in these locations from April to November, with measures to intervene where activity is detected. A parallel process monitors illnesses transmitted by vectors and acts on reports from members of the public relating to the presence of mosquitos.

Data generated by this work show that in 2023 the activity of mosquitos in public streets and squares in Barcelona dropped by 45% compared to the previous year, a downward trend caused in recent years by the drought.

Main breeding sites on private property

Despite the drop in the activity of mosquitos in the city, an important observation is that roughly 70% of tiger mosquito activity occurs outside on private property (gardens, terraces, yards etc.). A female can lay up to 200 eggs a week in small recipients where water has accumulated.

We therefore need to keep an eye on these, remove them, empty them or turn them upside down. Checking them every 5 to 7 days so that water does not accumulate in them is a simple and efficient measure that can be adopted at home to avoid tiger mosquitos reproducing. Particular attention needs to be given to the dishes beneath plant pots, drains, buckets, small recipients and toys.

To this end, this year brings the return of the campaign “In your home, let’s prevent tiger mosquitos”, aimed at reducing breeding sites for the species on private property through home visits in different neighbourhoods. Homes will be chosen in advance according to an analysis taking into account the characteristics of greenery on private properties and other factors.

The goal is to provide the public with information and raise awareness as a way of efficient prevention in private spaces and controlling the species. The visits offer an informed inspection, explaining how to identify potential breeding sites and what steps to take to eliminate them.

Factors that cause mosquitos to reproduce more

The rise in temperatures and accumulations of water make for more mosquitos, an effect accentuated by climate change. The lack of rainfall in recent years has meant that places in the city where rainfall accumulates are dry, leading to fewer breeding sites for the species.

It is worth noting that 2023 was the driest year since records began in the city, and the second hottest. Even so, the prevention of mosquitos remains a key factor in avoiding inconvenience and health risks for people.

The ASPB checked 40,633 monitoring and control points in 2023 (scuppers and ornamental and natural springs) in public space, detecting activity at 248 and carrying out 24,949 larvicide treatments with biological products that have no harmful effects for the environment or for people’s health. The agency also handled 143 reports from members of the public.