Tiger Mosquito Establishes Expanding Presence in Southern Andorra Parishes

The tiger mosquito has established a regular but expanding presence in Andorra's southern parishes—Sant Julià de Lòria, Andorra la Vella and Escaldes-Engordany—and the central valley, according to a government-led study.

Researchers from the Interministerial Commission 'One Health', which includes the Health and Environment, Agriculture and Livestock ministries, worked with Andorra Recerca + Innovació (AR+I). With support from the Mosquito Service of Baix Llobregat County Council, they analysed insect diversity nationwide during summer and autumn 2025. Teams set up traps for adults and eggs at multiple sites over eight biweekly campaigns from July to October.

Results showed consistent but rising numbers of eggs, larvae and adults in the affected areas. The final October round detected overwintering eggs, confirming the species' ability to endure winter conditions.

Health authorities note the insect's public health risks: frequent, irritating bites and potential to transmit viruses. It breeds mainly in small stagnant water collections, such as saucers under pots, vases, buckets or tyres, rather than flowing water or large bodies. This pattern underscores the need for household-level prevention by residents.

In response, the government and seven communes plan coordinated measures across three areas: a monitoring system to track distribution; awareness campaigns to encourage public action against breeding sites; and direct treatments at potential hotspots in public spaces.

The findings were presented to commune consuls last week, stressing citizen involvement to curb further spread.