Spain's coast has a daytime pest. Seville has a West Nile season.

A summer trip to Spain usually means some mix of Barcelona, a stretch of Mediterranean beach, Mallorca or Ibiza, and a few hot days in Seville. On the coast, most bites come from one insect, the Asian tiger mosquito, which was first found near Barcelona in 2004 and has spread along the Mediterranean since. In Spain it is a pest more than a health problem. The health question sits inland, in the river country south of Seville, where West Nile virus came back strongly in 2024 and again in 2026.

The tiger mosquito on the Mediterranean coast

The European Centre for Disease Prevention and Control (ECDC) calls the tiger mosquito a serious biting nuisance in Spain, one that significantly reduces quality of life where it has settled. That covers Barcelona and the Catalan coast, Valencia and the Costa Blanca, and the Balearic Islands, where the wetlands near Alcúdia on Mallorca have a reputation for daytime bites.

It bites in daylight, with peaks in the morning and late afternoon, and it waits in shade and around plants: café terraces, hotel gardens, villa patios, the potted geraniums on a balcony. It breeds in small pools of standing water, so a saucer under a plant pot is enough. Night-time precautions alone miss it. Our daytime mosquito routine has the full schedule. On a Spanish summer trip it comes down to three habits.

No local dengue or chikungunya in 2025–26

The tiger mosquito can spread dengue and chikungunya, and in recent summers it has done so in Italy and France. Spain has been spared lately. ECDC recorded no locally acquired dengue in Spain in 2025 or in 2026 as of October 21, and no local chikungunya in either year. ECDC's 2025 list of countries with local dengue names only France, Italy and Portugal's Madeira, and its chikungunya list for both years names only France and Italy.

Spain has had small dengue clusters before: 6 cases in 2018, 1 in 2019, 6 on Ibiza in 2022, 3 in Catalonia in 2023 and 8 in Tarragona province in 2024. A new one is possible in any hot summer, which is one more reason for the morning habit. There is no CDC travel notice for Spain, CDC lists no malaria medicine, and the yellow fever vaccine is neither recommended nor required.

West Nile around Seville

West Nile virus is spread by Culex mosquitoes, which bite mostly in the evening and at night. In Spain it recurs in the river lowlands of western Andalusia, along the lower Guadalquivir south of Seville, and in Extremadura around Badajoz, on the Guadiana. It is rare in the main coastal resorts.

The last three seasons show how much it swings. ECDC counted 138 locally acquired cases and 15 deaths in 2024, including 92 in Seville province. 2025 was quieter, with 36 cases, most of them around Badajoz. In 2026 the count passed 140 by late October, with Seville and Badajoz provinces accounting for most of them and a handful in Huelva, Cáceres, Cádiz and Málaga. Most cases come from river towns south of Seville. Most infections are mild or cause no symptoms, and ECDC notes that severe cases are mostly in people 65 and older.

The virus is also reaching new places in animals. In 2026 Girona, Huesca and Gran Canaria had their first-ever animal outbreaks, with no human cases reported there.

The Canary Islands' newcomer

The Canaries have a second invader to watch. Aedes aegypti, the yellow fever mosquito, is a stronger dengue carrier than the tiger mosquito, and it keeps arriving by ship. ECDC lists the Canaries among the places it has reportedly been introduced. According to regional media, La Palma was declared clear of it in 2023, specimens were found at the Santa Cruz de Tenerife cruise terminal in December 2025 and January 2026, and in October 2026 it turned up in the town center of Mogán, on Gran Canaria. No local dengue has been reported on the islands.

For a beach week on Tenerife or Gran Canaria, that means the same daytime habit as on the mainland coast, applied when you're out in town and in gardens. The islands tend to be lighter on bites than the Mediterranean side.

River flies and sand flies

Two more biters are worth knowing. Black flies, mosca negra in Spanish, breed in running water and bite by day near rivers. They are a recurring summer pest along the Ebro in Zaragoza and the Manzanares in Madrid, where both cities run control campaigns; Zaragoza used drones over the Ebro in June 2024. Repellent on exposed skin helps on a riverside walk.

CDC's Spain page also lists leishmaniasis, a parasite spread by tiny sand flies that bite from dusk to dawn. The evening repellent you're already wearing covers them, and an air-conditioned or screened room handles the night.

Where you're going

Here is how the main summer destinations compare for a June–September trip.

June to September, and either side

June to September is tiger mosquito season along the Mediterranean coast and in the Balearics, with the most bites in July and August. West Nile risk around Seville and in the Guadalquivir and Guadiana lowlands rises from July into September; across Europe, 2026 cases peaked at the end of August.

Spring and fall are easier, though not bite-free. On the coast the tiger mosquito stays active from spring well into the fall, so a May or October trip still calls for daytime repellent, with fewer bites. West Nile cases cluster in late summer, so a spring visit to Seville falls outside the main season.

What travelers report

Paraphrased from forum threads and linked so you can read them in full. None is dated to this season, and individual trips vary with weather, wind and where you stay.

• Valencia · May

  In a thread about four years old, replies described the tiger mosquito as a daytime biter that is quiet and slow, so easy to swat, and linked it to damp soil and foliage. Posters recommended DEET and Autan sprays; one said the species is found across southern Spain and the Balearics from about April to November. TripAdvisor ↗

• Seville · summer

  In a thread about two years old, a traveler asked about mosquitoes and West Nile. Replies noted the high number of West Nile cases in Seville province that summer and local protests in Coria del Rio and Isla Mayor; one poster thought the risk to visitors was exaggerated. TripAdvisor ↗

• Mallorca (villa near Pollensa)

  A group staying at a villa reported that all five adults were bitten by mosquitoes or biting flies during the day and evening, and that a DEET repellent had little effect. Another poster said bites came through clothing; others blamed the daytime tiger mosquito, which rests around potted plants and hedges. TripAdvisor ↗

One more rule outlasts the trip. Any fever during or after your trip means a doctor visit, and you tell them you were in Spain. After a late-summer stay around Seville, fever with a headache, stiff neck or confusion needs prompt care, and naming where you stayed helps the doctor think of West Nile.

Traveler questions